describe:1. Suitable for handlebars with a diameter of 22.2 mm. Compatible with V-brake systems and cable disc brakes (mechanical disc brakes). Great for most mountain bikes, folding bikes...2. Visual display. Designed with an optical gear display indicator to display the gear position.3. 3-speed left brake lever, 7-speed right brake lever, total 21 speeds / 3-speed left brake lever, 8-speed right brake lever, total 24 speeds (optional).4. The package contains a pair of left and right brake lever shift lever kits. Equipped with transmission cable.5. Easy to stall. Aluminum alloy brake lever. Brake cable made of stainless steel.Specification:Dimensions: 17.5 cm x 8 cm x 3.5 cm (6.89 in x 3.15 in x 1.38 in)Weight: 350 g/pairMaterial: aluminum alloyHIGH QUALITY: Made of high quality plastic material, durable.packing list:1 pair left and right brake lever shifter kit