Gearbox adapter. CNC technology made of ultra-durable 2017a duralumin, then hand finished. High precision and fit guaranteed. Engine: Nissan RB20 / RB25 / RB30. Gearbox: BMW M50, M52, M57. 2017a duralumin, then hand finished. Guaranteed high precision and fit. Engine: Nissan RB20 / RB25 / RB30 Gearbox: BMW M50, M52, M57