Size (W x D x H): 0.7 x 0.7 x 1.9 inches (18 x 18 x 48 mm); Weight: Approx. 0.2 oz (5 g); Material: ABS (Acrylonitrile, Butadiene, Styrene) resin; Country of Origin: China; Set Contents/Accessories: 4 x Main units; Compatible models: All models *May not be possible depending on the type or shape of helmet.