If you are the type of reloader who prefers to choose the type of primer you use, these RCBS APS Unprimed Primer Strips are a great option. RCBS APS Unprimed Primer Strips do not come with any primers, so you can fill them as you desire. RCBS APS Unprimed Primer Strips are coded by color to make it easy to identify the type of primer you are using, and each unprimed strip can hold up to 25 primers. This particular set of primer strips is yellow, which means that they work with #200 standard large rifle and #400 standard small rifle primers.