if your talking about www.stsmicroengines.com and/or www.nitrocountry.com for some reason those two places are having a hard time getting STS stuff, but the link I gave you (in the post above) I bought mine form that guy, he said he's having NO problem getting STS stuff, and it looks like he may be the only STS dealer in the US if the other two place can't get anything in stock.

and projectzen has the best prices on the 21B