矩形截面密封圈-Square-ring
Benefit：
Uses same groove as o ring
Can be used for radial sels
Material is homogenous, no joints, no laminations
Edges accurately formed
Close tolerances held on cross-section, I.D. and O.D.
Controlled surface smoothness, hardness, elasticity, toxicity, texture
The modern, economical option for static application.
Available in many compounds
