Where to get bumper mounts?

[Magice]

I'm talkin about the little foam things that attach your bumper to kart body. I'm either not mounting them properly or need new ones. Where abouts would I get them from?

[Magice]

http://www.out2win.com/catalog/images/PR0073.jpg

Finally found what I was talking about.
Any particular size I need for my kart? It's a run of the mill racing kart.