SVBONY Reticle Illuminated Eyepiece 1.25inch 12.5mm Double-line Crosshair 4-Elements Plossl Design 40-Degree FOV

This is a terrific product once you figure out how to assemble and operate it without instructions. You will get it with 3 small watch/hearing-aid style batteries. Screw apart the illuminator in the middle. The batteries go into the half with the clear plastic tube that has a small round battery contact inside. The batteries go button side down, flat side up, into the tube. Stack all 3 batteries the same way, then screw the other half of the illuminator back on. You should be able to see the red light come on at the end of the illuminator when you click the switch knob on and turn it all the way bright. Screw the illuminator into the hole in the side of the eyepiece. Turn off the illuminator light and look through the eyepiece in normal room or day light and see the four black crosshairs. Most likely they will be very blurred. The ring on top of the eyepiece is for focusing the cross-hairs, so turn it as many turns as needed to get the two double cross hairs into sharp focus, and you're done. When using it at night through your scope, adjust the illuminator brightness as needed, depending on how bright your target is. On "first light" with this eyepiece, I achieved the best alignment that I've ever experienced with my Alt-Az mount.