This is a LEGO TECHNIC®-compatible 40-teeth ring gear.
Combine together with companion parts and LEGO TECHNIC® gears to build amazing reductors or gearboxes:
This product is in no way endorsed by nor affiliated with the LEGO Group. The LEGO® and LEGO TECHNIC®trademark are only named here to suggest this product is compatible with the LEGO® line of toys. It is an original design and not a copy of a branded product.