Fork body and pin: Aluminum, anodized, black
Fork pin shaft safety retaining clip (KL and SL versions): Spring steel, hardened and tempered,
zinc-plated and blue passivated
GN 751-AL fork heads are mainly used with pneumatic or hydraulic
GN 751-AL fork joints consist of a fork head with KL-shaft safety or SL-shaft safety retaining clip.
Type KL (top photo version) is a "single" shaft safety retaining clip; only one side secures the pin in place (and therefore if bumped in the wrong way, may slip out of place).
Type SL (bottom photo version) is a "double" shaft safety retaining clip; both sides are raised to secure the pin from both directions. To remove this shaft safety retaining clip you must pull up on the spring sheet metal.
Due to the anodized coating of the fork head and pin, this component is virtually non-wearing.