Denis, these are reusable. You just load the stripper clip with ammo, open the bolt of the sks and use the stripper clip to push the ammo down into the magazine. You don't have to remove the magazine. Id recommend you to Google ( how to use a stripper clip sks ) and they'll have videos of how to use them. Hope this helps.

Denise, you use these over and over to assist you in loading the magazine, and the magazine need not be removed to use it. You can load all 20 before you go to the range to help make reloading easier. Have a great day!

Denis, they are reusable Sir. It will work no issue with the fixed magazine as was originally designed to. Cheers and stay safe!