They were fun in their time as they would hold 14 rounds of .223/5.56, but caused lots of double feeding issues as they got older because of the weak plastic feed lips.
There were also some Alexander Arms metal .50 Beowolf mags pinned to 5 rounds that were available, those would also hold a little over 10 rounds of .223/5.56 depending on where the rivet was installed, but they were going for around $80+ per magazine. They were much better fuction wise compared to the PCV's, and they were licesnced .50 Beowulf mags so people felt safer law wise using them. However like most things our GOV ruined the fun on those eventually, you could only find them pinned to 2 or 3 .50 Beowulf after they changed their import rules on them, leaving you with the normal 5 rounds of .223/5.56 capacity.