The Mesa SureShell Polymer Side Saddle system combines a 6-shell carrier with a 4 3/4" Picatinny rail for Mossberg 500/590A1/Maverick 88 shotguns featuring durable glass-filled polymer construction.Mesa SureShell Polymer 6-Shell Carrier SystemCompatible with Mossberg 500/590A1/Maverick 88 (12-gauge)4 3/4" Picatinny rail machined from aircraft grade 6061-T6 aluminumGlass-filled polymer shell holders with dual rubber friction systemLightweight aluminum back plate with brass threaded insertsMIL-STD-1913 Picatinny compliant with mil-spec hard anodized finishNo gunsmithing required for installationPerfect for tactical applications and sporting use this system provides reliable shell storage and a robust mounting platform for optics while maintaining the shotgun's streamlined profile.