This kit uses a unique

Weight 125 grams

These are for use with 104 BCD chainrings or 64 BCD chainrings on 104 BCD cranksets

The compact design delivers up to 500 lumens with eight different modes

This model replaces the older SM-HB20 Lock Ring

absoluteBLACK Direct Mount Narrow Wide Chainring - SRAM Direct Mount - 3mm Boost - Oval - Gold - 9-12 Speed - 28T Ignore Wholesale Tier 1 Brand Rule This kit uses a uniqueabsoluteBLACK is dedicated to producing the world's finest oval chainrings and were the first to crack the code to discover the correct shape and 'clocking' to make an oval chainring work. They learned how to maximize the part of the stroke where power is produced and minimize resistance where it isn't. The oval shape smooths the delivery of power throughout the pedal stroke and improves efficiency and energy conservation. Many other brands have