Bouts = "leftover" randomly-shaped trapezoids/rhomboids/etc. that remain after first extracting as many rectangles as possible.  For the record, they obviously had bouts available to them miners to try and sell a century and a half ago, too...I guess back then they assumed there'd be plenty of rocks forever.

Bouts are great for establishing bevels, and present no limitations at all for water-only finishing to me.   Depending upon their shape, they can be limiting for going from bevel-making to the final finish via continually watered down slurry, and thus you can see the rationale behind why my primary preference is for stones with ultra-high water-only speed.   With enough square footage (particularly in any one long axis), bouts are absolutely fine and of no meaningful difference.   Bouts are always the best value per unit of area, too.

Bouts are cool; I'm privileged enough to say I was once briefly an Aspen, Colorado ski bum (94-95, ask me about mid-Feb. when we had ~100" in 10 days followed up by 26" after the lifts closed and before they opened, people were hurling themselves off the Steeplechase edge just to land in bottomless chicken feathers), and bouts remind me of skiing Aspen Highlands instead of Aspen Mountain.   While the latter's more famous, nearly every run falls straight to earth...most runs on "Highlands", however, simultaneously fall down and to a side.  In this opinion, one learns more of skiing in that complex realm, and one will better learn honing's essence on a bout than on a rectangle.  Honing's primarily about what you're feeling with any one part of the edge at any one time on any one part of the stone.   Become accomplished living that philosophy and you can hone upon circles.  To loosely quote the brilliant 1980 masterpiece Caddyshack, "be the edge" :-)

• # 3 Bouts = 22-27 sq. cm a perfectly-average "perfect" parallelogram would be 1.9 x 1.9" (49x49mm)
• # 4 Bouts = 27-33 sq. cm a perfectly-average "perfect" parallelogram would be 2.16 x 2.16" (55x55mm)
• # 5 Bouts = 33-39 sq. cm, a perfectly-average "perfect" parallelogram would be 2.4 x 2.4" (60x60mm)
• # 6 Bouts = 39-48 sq. cm, a perfectly-average "perfect" parallelogram would be 2.6 x 2.6" (66x66mm)
• # 7 Bouts = 48-58 sq. cm a perfectly-average "perfect" parallelogram would be 2.9 x 2.9" (73x73mm)
• # 8 Bouts = 58-70 sq. cm a perfectly-average "perfect" parallelogram would be 3.15 x 3.15" (80x80mm)
• # 9 Bouts = 70-84 sq. cm, a perfectly-average "perfect" parallelogram would be 3.45 x 3.45" (88x88mm)
• # 10 Bouts = 84-102 sq. cm, a perfectly-average "perfect" parallelogram would be 3.8 x 3.8" (97x97mm)

What lies below is amongst what we're best known for as a shaving shop.

The most challenging bout (polygon) shape to me is an isoceles triangle, and the easiest a parallelogram.  With plain water use for touch-up/finishing work, to me any shape's of no limitation.

If you'd like to have a stone with the geometric advantages used by all Solingen master grinders, we can supply it!  [full disclosure; in Germany they prepare these entirely by hand and it takes on a dual-axis convexing, what's offered here is strictly a sphere]   This service option gives you a convex stone, not a flat one...use your slurry stone upon it in circles moving away from the 'summit' of your hone to generate wear away from the middle that we tend to use the most, and it should be able to maintain the convex shape perpetually.  The convexing is subtle but nonetheless perfectly represented and quite uniform in a spherical gradient.

Why do they (all) do this where they're made?  Because 1) it reduces spine wear, 2) it solves all problems with warped razors or razors of varying thickness, 3) it isolates the contact patch to a narrow point to provide better feedback, 4) it guarantees that with each stroke the entirety of the spine and edge will receive contact, as opposed to a variably-thick razor being used on a 'normal' flat stone which will merely grind away the thickest parts of the razor until all is of one width, and 5) it makes the bevel plane angle marginally more acute than is possible with a flat stone (actually the master grinders by and large prefer to use flat wheels/belts until the bench stone, and the bench stone is only to alter the acuity of the very last bit of the bevel plane width rather than cut in an entire bevel plane with the increased acuity).  Give it a good think and consider the worth of this for yourself, don't let others online or here do your thinking, but remember that the use of the convex hone is univeral in Solingen and the proof of proper preparation of such a benchmark test during one's apprenticeship.

Convex My Coticule
$10 In-Stock (duh)

Ardennes-Coticule had to unfortunately increase their prices considerably in 2018 to have investment capital needed for further extraction down the road... we are all lucky that a familial team exists that's willing to still fetch Belgian coticule from the earth at all, for there are surely many beautiful whetstones locked safely away underfoot only because less parties are willing to till the soil for their time.  The very good news for you incumbent owners of Belgian coticules is that your resale value of your stones will certainly rise as the retail prices rise, and the same will occur for eBay/etsy/etc., but in the meantime we do have a small selection of bouts which were extracted from the ground prior to 2018 and we offer these to you for the same mark-up rates as we do for the 2018 rocks we'd paid much more to acquire...first come, first served!

Each includes a free slurry stone, they were not marked for any 'vein' by Belgium, and have already been lapped flat.   Here are my prejudgements from about 1 minute messing with each one w/ a razor; the 5th and 7th have a purely soft texture that is similar to the 'La Grise' that they were extracting and shipping almost exclusively from >2011 <2014 (though I doubt that they are, in fact, 'La Grise', probably something new, but plays similarly), the 2nd/3rd/6th/8th have a quite fast semi-hard texture.   USA ONLY:  email for a non-USA custom quotation, include any other items and your location and we'll determine lowest possible extra expense vs equivalent domestically.

Each includes a free slurry stone, they were not marked for any 'vein' by Belgium, and have already been lapped flat.   Ignoring all aspects of names/shapes/size/depth/price, I will characterize the surface texture of #1 as preferred to all others, and - while in our human lifetimes it isn't especially relevant unless you are one hell of a prolific honer - the 2nd and 4th stones exhibit that they came from a slice which was damn close to the confluence of the next 'layer'/'vein' of coticule...(often these pcs will exhibit characteristics which are like cross-pollination hybrids).  USA ONLY; email for a non-USA custom quotation, include any other items and your location and we'll determine lowest possible extra expense vs equivalent domestically.

Each includes a free slurry stone, they were not marked for any 'vein' by Belgium, and have already been lapped flat.   Ignoring all aspects of names/shapes/size/depth/price, I will characterize the surface texture of #1,2,3, & 5 as preferred for me, in that order.   USA ONLY:  email for a non-USA custom quotation, include any other items and your location and we'll determine lowest possible extra expense vs equivalent domestically.

Each includes a free slurry stone, they were not marked for any 'vein' by Belgium, and are shown as received; elect to have yours lapped the regular flat way or convex like the master grinders use.   I would say with the very slight exception of #3 which has a hint of abrasive sensation at the righthand side of the pics region, these are all four cut from the same cloth that resembles the slower/softer/messy/malleable stones which used to be in near-universal supply from about 2012-2015.  This is something new, though, because its feedback sound has a slight treble sensation that is completely unlike the '12-15 holographic La Grises, and you can't bear down on these as much nor will they require as much lapping as those oldies (if you're having trouble with any old La Grise, you need to use more water and more pressure; their annoyance beyond their sloth is like the fine Naniwa Super Stone 12000 in that they'll need reflattening often).   A firm touch will help here, but it isn't the kind that will kick up free slurry by its lonesome.   USA ONLY:  email for a non-USA custom quotation, include any other items and your location and we'll determine lowest possible extra expense vs equivalent domestically.