Item Type: Pick Roller_x000D_ Material: Silicone Rubber_x000D_ Hex Hole Inner Diameter: Approx. 5mm / 0.2in_x000D_ Width: Approx. 16mm / 0.63in_x000D_ Hardness: 30A_x000D_ ModelOD(Approx.)_x000D_ 5618-4008-001212mm / 0.47in_x000D_ 5618-4008-001616mm / 0.63in 1Reliable Parts: Enables strong grip to cooperate with other shaft, column and so on to form excellent robot component. 2Hex Inner Hole: The hex inner hole is highly compatible with both round and hex shaft for stable working performance. 320Pcs in Total: There are 20pcs pick roller in the set, and the large quantity will simplify your DIY robot assembly. 4Great Material: Adopting high quality silicone rubber with 30A hardness, very reliable and durable for long term use. 5Easy to Install: Comes with a compact size as well as a light weight, the easy installation can be quickly finished.Match the proper size before use.20 x Pick Roller