Hot Toppers offer a great product, along with customer support. I've installed two full sets on two bikes and never had an issue of the chrome failing and them coming loose.

 

+1 on what everyone here is saying. Looks better then rusting chrome hexheads etc. Rarely lost one, those were replaced and siliconed in place. A buddy has a nighttrain with them; really looks sharp!

My HD parts guy has the full sets & boxes with individual sizes too. You can buy just one or as many as you like. No need to put them where the sun don't shine.