M42-M42 Spacer - 21mm

Finally got the right spacing for my reducer with these threads—screwed on perfectly and didn’t have any wobble. It’s exactly 21mm as advertised, so no more guessing with shims.

Finally a spacer that actually measures exactly 21mm on my calipers. The threads are smooth and catch cleanly, which made getting my camera sensor to the perfect back focus a breeze.

Was worried about getting the exact back focus distance for my telescope, but the double female M42 threads make it really straightforward to stack with other rings. Arrived quickly and the threads are clean without any binding.