This 1.25" cap allows you to protect your 1.25" eyepieces. It fits on the barrel end (base) of the eyepiece that you insert into the focuser. It is made of soft yellow plastic so they are quick to put on and take off, and easy to see in the dark. It also fits over the top ('eye end') of Celestron/Vixen silver top Plossl eyepieces. For caps to fit the top of other 1.25" eyepieces, please see the other items in this store. Because it is made of soft plastic the eyepiece cannot be stood on end.