Bandit slim line retainers are designed to fit Mach 1 Fiberglass better than any other retainer on the market.  Some highlights of these retainers are:
 
Low profile retainer perfect for boat tail applications and tight spaces 
 
 Anodized gunmetal grey retainer 
 
Designed to fit Mach 1 fiberglass tubing perfectly 
 
The first of these retainers are for 29 mm with more to come in the future.