Not currently. At least I couldn't find any on their site...
Not sure if they are discontinued, out of stock, or what... I know they stopped making 45->10mm conversion barrels, too.
I think I read somewhere the G20 and the G21 frame were the same. I called lone Wolf around noon to ask, but the phone was busy.
You might want to call and ask them. You can also put .357sig, 40S&W and 9X25 dillon barrels in the 10mm slide.
*This custom LWD-SLIDE20T is the same OAL as the factoryG34 & G35 Tactical slides 8.15 inch or 207mm. This slide requires a 5.15 inch barrel. Fits Gen3 G20, G20SF frames and accepts all Lone Wolf conversion barrels 40 S&W, 357 Sig, 9 x 25 Dillon. Will also allow you to easily convert your Gen3 G21 or G21 SF to fire 10mm.