Rocketarium Aluminum Motor Retainer 24mm ROC-RK-91240
24mm Aluminum Rocket Motor Retainer for Estes (standard), Rocketarium (standard) and Apogee tubes with O.D. 0.976"
Retainers are used in place of the hook. It makes it easier to install or remove the motor from the engine mount.
For use with BT-50 tubes and 24 mm motors, including Estes/Quest 24 mm D-E motors, Cesaroni Pro24, Aerotech single use and Reloadable 24 mm motors.
Once installed, the retainer doesn't require any tools to operate. Simply install the model rocket motor, and screw on the cap.
Detailed instructions are available online
The 24mm retainers also allow you to use 18 mm RMS system with rockets requiring 24 mm black powder motors. All you need is to install the retainer and add 24 to 18 adapter.