I bought a new Atomstack M50 laser (10W) which works great.

However, my existing Air Assist came with a shorter window.

This extension blocks the empty space, so the laser light won't come flying out the top, and the laser+fan assembly remains “enclosed”, so you can use your older Air Assist without blinding yourself. Probably a good idea to wear laser safety glasses anyway.

Remember to attach your hose and the nozzle BEFORE sliding in the window, and to be very gentle with the grub screw (so you don't break the window glass.)

Printed in Red opaque PLA (nothing special about it, just what I had on hand.) 30% infill, .28mm layers. (Probably doesn't matter, do whatever makes your printer happy.)