This lets extra small bike frames to be carried by a rear mounted car racks (by allowing more room between the frame tubes when cages are removed) and prevents cage damage by rear type bike carriers. The perfect solution for preventing damaged bottle cages for all bike frame sizes. Material: Aluminum/ Engineering Grade Plastic. Mount: Water Bottle Boss Mount Size (L x W x H): 10.9 x 4.4 x 9.5 cm, 4.3” x 1.7” x 3.7” Weight:32.6 g / 1.15 oz