What Size Bobber Stop For 15-20 mono?

Want to start using a bobber stop. Looked at some of them online. Some have small, medium, and large sizes. Others don't mention a size. Saw some on eBay also for very reasonable price. Are all bobber stops neopreme/rubber?

What do you recommend for 15-20 lb mono line?

Thanks!

Found the answer. Will use large size.

Eagle Claw Bobber Stop

I like these and they're super cheap! I like em' because they fit all sizes of lines, big or small. They hold up well and they're tiny! I can bang em' against rocks and timber all day long and they don't chip or bust. Great little bobber stops!

http://www.tacklewarehouse.com/6th_Sense_Peg_X_Stoppers_9pk/descpage-6SPEG.html these are the best.

These are the best made trust me.

Most are rubber....We will send you some to try out. Send us your shipping address via PM. Thanks