Polaris RZR 900S UHMW A-Arm Guards. Factory UTV RZR 900S Series UHMW a-arm guards offer the best in a-arm protection. Constructed from ultra tough and slippery UHMW these guards protects your a-arms from the off road abuse you love to put them through. Factory UTV UHMW armor is the gold standard of UTV protection products. This is the same protection Factory UTV Support racers have used to protect their race UTV s and win every major Pro UTV Endurance Championship race including the Baja 500, Mint 400, King of Hammers, San Felipe 250 and Silver State 300.