Question 1

What do S and R mean on C-type retaining rings?

Accepted Answer

S is for shafts (fits an external groove on the shaft, DIN 471) and R is for bores (fits an internal groove in the bore, DIN 472); the number that follows is the shaft / bore diameter (mm).

Question 2

Are external and internal retaining ring pliers the same?

Accepted Answer

No: external rings need pliers whose tips spread open, internal rings need pliers whose tips close. SFP also sells convertible and dedicated retaining ring pliers.

Question 3

What materials are C-type retaining rings made of?

Accepted Answer

Common options are black oxide carbon steel (spring steel) and stainless steel, plus phosphate coated; for corrosion resistance choose stainless.

	External / for shafts (S-ring / STW)	Internal / for bores (R-ring / RTW)
Installed in	An external groove on a shaft	An internal groove in a bore
Standard	DIN 471 / JIS B 2804	DIN 472 / JIS B 2804
Designation	S + shaft diameter (mm), e.g. S10	R + bore diameter (mm), e.g. R32
Installation tool	External ring pliers (tips spread open)	Internal ring pliers (tips close)

C-Type Retaining Rings: External S-Rings (DIN 471) vs Internal R-Rings (DIN 472)

Black oxide S-rings (external) in stock

Stainless steel S-rings (external) in stock

Black oxide R-rings (internal) in stock

Stainless steel R-rings (internal) in stock