I bought a ken onion edition years ago and it came with these belts Includes: (1) P120 Extra Coarse Grit, (1) X65 Coarse Grit, (1) X22 Medium Grit, (1) X4 Fine Grit, (1) 6000 Extra Fine Grit For $20-$25 you can find packs of 30 silicon carbide belts that come with 5 or 6 grits between 80 and 1000. Just make sure which size you need, 1x12s or 1x18s depends on which attachment you are using. More on reddit.com

So MK 1 & 2 are the same belts. It's whether or not you use the blade grinder attachment vs the stock guide. Blade grinder mark 1 and 2 are 1 x 18 and my favorites are any stiff silicon carbide belts with grinding lube added. The stock setup with guide I've never used are 1/2" x 12"? 45 Pcs 1/2" x 12" Replacement Sharpening Belt Kit for Official Work Sharp Knife & Tool Sharpener (WSKTS & WSKTS-KT/Mk.1 & Mk.2) - 80/120/240/400/600/800/1000/2500/5000 Grits https://a.co/d/g3DvE3g Give these a go? For the price it's worth it just to experiment. Edit: you can make huge jumps with belts so I'd try 240/2500 for a two belt; 120/1000/5000 for a three belt progression; or just a 400 and a stropping if you don't need to do heavy repairs for a single belt. More on reddit.com

Worksharp themselves make many different belts. But if you just search the size on Amazon I believe they have many different options More on reddit.com

As a follow up, here are my 1st impressions. To cut to the chase, its a keeper! Like the difference between a Ford and a Cadillac I believe they used to say.  Both do the same thing, just in a different way.  The new WS has much less vibration and the rollers supported on both sides make all the belts run truer without flutter and with much less noise.  Didn’t expect that honestly, but it simply makes sharpening much less stressful without the noise/vibration.Had to learn a way to release the belt tensioner lever because the spring is so strong.  Finally figured it out by putting my left hand ‘behind/at the head’ of the BGA and then pushing the lever with my thumb.  That used to be a one hand job, but at least for me, no more.  Still adapting to routing the belts, especially the thin/flexible ones.  I’ll get it, but for now requires me to bend to the right to see what I’m doing because of the narrow available path to slide the belt into.All the new gadgets work as advertised including the moveable large roller.  Absolutely love the flatter bevel profile I can now get in the 3rd roller position not available on the original!  Another big plus is that there is now a metal ‘platen’ on the backside allowing absolutely flat grinding on things like scissors.  A big plus for me!  I had to install a piece of leather on the original to take up some space because of belt flex at that area.  No longer necessary as the belt runs cleanly directly against the platen.I also used the new V shaped sharpener with the guide off to sharpen some hedge clippers and found the same characteristics as the BGA, quite with less vibration and better belt tension.  Works great. More on reddit.com