a ims ▁V IS 5 0 0 ▁use ▁inf ra red ▁LED s ▁which ▁are ▁placed ▁above ▁the ▁target ▁and ▁are ▁recogn ised ▁by ▁the ▁camera ▁module ▁within ▁the ▁aim ing ▁device . ▁Sho ot ers ▁who ▁comp ete ▁in ▁wheel ch airs ▁( as ▁shown ▁in ▁the ▁photos ) ▁comp ete ▁in ▁special ▁wheel ch airs ▁which ▁comp ly ▁with ▁the ▁gover ning ▁body ' s ▁reg ulations . ▁These ▁wheel ch airs ▁have ▁relatively ▁low ▁back ▁support ▁and ▁no ▁arm rest s . ▁The ▁mechanical ▁support ▁is ▁used ▁to ▁bra ce ▁the ▁rif les ▁for ▁shooting . ▁ ▁W heel ch air ▁racing ▁ ▁W heel ch air ▁racing ▁equipment ▁designs ▁were ▁limited ▁from ▁the ▁ 1 9 4 0 s ▁until ▁the ▁ 1 9 9 0 s , ▁these ▁restrictions ▁greatly ▁in hib ited ▁the ▁innov ation ▁and ▁design ▁of ▁racing ▁wheel ch airs . ▁Modern ▁racing ▁wheel ch airs ▁have ▁been ▁developed ▁sole ly ▁for ▁speed . ▁Hence ▁they ▁use ▁large ▁rear ▁whe els , ▁a ▁long ▁wheel base , ▁small ▁hand ▁r ims ▁and ▁a ▁forward - lean ing ▁bucket ▁seat . ▁There ▁are ▁three ▁methods ▁to ▁ste ering ▁racing ▁wheel ch airs , ▁by ▁using ▁the ▁handle bars , ▁the ▁compens ator ▁or ▁by ▁doing ▁a ▁wheel ie . ▁ ▁The ▁wheel ch airs ▁used ▁at ▁the ▁beginning ▁of ▁wheel ch air ▁racing ▁were ▁slightly ▁modified ▁every day ▁ch airs . ▁Modern ▁racing ▁wheel ch airs ▁are ▁made ▁of ▁advanced ▁materials ▁such ▁as ▁tit an ium