Original equipment replacement part. Genuine replacement parts When it's time to refresh your trusty light, Trek Genuine Replacement Parts have you covered. - Securely attaches all Ion lights to bars Securely attaches all Ion lights to bars - Reduces vibration and slippage Reduces vibration and slippage - Mount rotates left and right for optimal placement Mount rotates left and right for optimal placement - Compatible with 31.8-35mm diameter bars Compatible with 31.8-35mm diameter bars - Compatible with 25.4 mm bars with optional rubber shim Compatible with 25.4mm bars with optional rubber shim