A....3.4mm x 2.0mm x L6.0 mm,3.4 is diameter of outside,and 2.0mm is inner diameter,L6.0mm is length;
B....5.0mm x 2.8mm x L3.0mm,5.0mm is diameter of outside,and 2.8mm is inner diameter,L3.0mm is length;
C....4.0mm x 3.0mm x L4.0 mm ,4.0mm is diameter of outside,and 3.0 is inner diameter,L4.0mm is length;

D....4.5mm x 2.0mm x L2.6mm ,4.5mm is diameter of outside,and 2.0 is inner diameter,L2.6mm is length;

Newest Silicone inner Micro ring ,All size picture showed available .