Shop @ RocketReviews

This extended-length engine hook is designed for use with standard-length (2.75") motors.  The extra .25" length allows the motor mount's thrust ring to be placed inside the hook creating a stronger, more secure engine mount.

Here is how a typical motor mount is assembled with a standard 2 3/4" engine hook. Note that the top of the engine hook is below the engine block.

When the ejection charge fires to deploy the rocket's recovery system, the motor pushes back against the engine hook.  Especially with the stronger ejection charges we are now seeing, this can enlarge or even tear the slit holding the upper bend of the engine hook. 

With the longer XL EH engine hook, the top of the hook is located above the engine block. This locks the engine hook in place, preventing it from sliding backwards.  There can be no movement of the engine during thrust or ejection.