I use this one that I had on my CRF250X
It works great because it does not suck the gas tank down tight to the frame which does cause stress on the tank and then eventually leak.
I put a bit of Blue Loc-Tite and mine and never had any problems loosing it.
http://www.crfsonly.com/catalog/prod...oducts_id/3467
The red electrical tape is there to add just a bit more thickness to fit snug on the gas tank.