Red Line RL-600 High Performance Brake Fluid - 500mL Color_Red/Black/Grey The larger 4mm hole is

The larger 4mm hole is used with Bell SRV-style shields

and of course steps

or lost side/top air mounting screws on your Bell BR-1 or GTX

mounting tray

Red Line RL-600 High Performance Brake Fluid - 500mL Color_Red/Black/Grey The larger 4mm hole isRed Line RL600 is a high performance DOT 4 synthetic brake fluid, engineered to maintain viscosity, lubricity and low compressibility under extreme braking loads. With a dry boiling point around 316 C (601 F) and a wet boiling point near 201 C (394 F), it offers superior resistance to brake fade, vapor lock and fluid breakdown. Perfect for serious street track hybrids, HPDE builds and weekend racers who demand reliable braking performance.