This part replaces the third chainring since most single-track riders seldom use it, but very often get hit by rocks that harm the chainrings. Designed to protect your middle and inner chainring. Covers up to 34 T ring (also works with 32 T). 6061 T651 US Aluminium. Anodized. 4 volts. 104 mm BCD. Weight: 90 g.