Please check on the individual chair pages to ascertain which options are available for that particular model. PU12 Fixed loop arms PU45 Height/width adjustable T arms PU55 Articulating ratchet arms PU250 Height/width adjustable T arms PUGF12 Gel/Foam option for T arms C Arm Height adjustable C arms WT Arm Height/width adjustable T arms STO2 Ring stool kit (base/casters not included) CA02 Hard floor casters GL02 Fixed glides SM27/SS1 Seat slider back to top