I love these adapters as you can fix them permanently to your 1.25" eyepiece barrel via a supplied grub screw. They also come with a 2" end cap so you dont need to worry about finding an end cap to put on when not in use. In the winter, when wearing gloves, I don't want to be messing with adapters and taking them on and off (risking dropping something), and these are the perfect solution! (Also note that the pictured thumb screw can be removed if using the grub screw as it is redundant). Highly recommended.