You're looking for 3 ML vinyl, or something close to that. Sign shops are great....do a google search......I order mine from Bowmanhunter, www.bowmanhunter.com or he's also on ebay.....The ones I get from him are $8/dozen plus postage. Not bad.

I am fortunate that I work in a factory that deals w/ 3.25ML vinyl.....I grab up the scrap sheets and cut them into 1x7 wraps. They are just solid whit but work well.