The Zero Tolerance 0550 and 0551 knives are a smash hit due to their combination of near custom quality, extremely modern materials, and the excellent designs skills of Rick Hinderer. Now you can buy accessory scales to customize your ZT 0550 or 0551 directly from the man that designed the knife.
The Hinderer Knives ZT 0550/0551 Scales are available in several colors, including my favorites: orange and translucent green. There are even camouflage options. The scales are machined from G10 which is resistant to just about everything (chemicals, heat, breakage, etc). The XM texture that Hinder Knives uses on these scales is touted as being easy on the hands while still providing plenty of grip and, based on the XM-18s that I have handled, I believe it.
The ZT 0550/0551 Scales are available on the Hinderer Knives website.