David, while I use chip tubes instead of flips, I think the rigid plastic flips are the better ones, because they don't have PCV in the plastic. The more pliable ones may have PVC, which can harm chips, and especially discolor coins/tokens over time.

Check with Charlie Rodgers at C.T.Coins for flips and other supplies (see his ads in the club magazine.)

If my info about flips is incorrect, I'm sure a more knowlegeable collector will chime in.