This OMP protective sleeve is a mandatory foam cover for your hoops with a diameter of 30mm to 40mm. Approved by FIA 8857-2001. Color: simple (black) Inner diameter: 30-40 mm Length: 490 mm. 2017 WRC regulations (FFSA recommended): All parts of the roll bar that a team may touch during a crash must be covered with FIA foam. (circled in the diagram)