... adjustable,easy to install diffuser neck size,plastic diffuser with neck adjustable ceiling diffuser hvac plastic diffusers supply ... square neck square ceiling diffuser square ceiling diffuser with neckShaping Mode: plastic injection Mould Steel: S45C, P20, 718, 718H, 2738, ... , NAK80, SKD61, E420, etc. (For Reference)Mould Base: LKM or Self-made.Mould Components: HASCO, DME, PUNCH, JINHONG, etc ( ...