... ; 4) 12 years in manufacturing; 5) OEM 1) 2 rings, 3 rings, 4 rings...2) Ring shape: R(O), D, Q, A ... metal ring binders according to numbers of rings. For example, 2 ring binders, 3 ring binders, 4 ring binder…etc. More ... Co. LTD. is a professional manufacturer engaged in the research, development, production, sale and service of loose-leaf binder mechanisms and ...