These mounts are well worth the time they save in fabricating an antweight. The bearing helps remove support the motor. Some of the threads needed cleaning up a bit with a 4/40 tap. Quality is otherwise very good.

Ever since I started using these bearing blocks, my silversparks have not broken. My ant hit the 4 foot roof of an arena, landed right on the wheels, and the drive motors were fine.
Definitely the best choice for motor mounts

These add so much strength and are so easy to add to the 3mm shaft on the Silver spark motors

After I switched to bearing blocks for mounting my Silver Sparks, I have not lost a single gearbox after fighting some of the nastiest spinners on the east coast. Glad I made the change.

I use these with silver sparks, gold sparks, and N20 micro gear motors. Not only are these great for taking stress off of motor shafts, but are fantastic when used for structural support.