The RD4.7F is a Zener diode, a two-terminal semiconductor device that conducts in reverse bias once the voltage across it reaches its Zener voltage. It is used in voltage regulation, clamping, and reference circuits across power supplies, industrial controls, and general-purpose electronics.
Bulk packaging — shelf and handling note
Store the parts in a dry, static-safe environment; Bulk units lack the moisture-barrier bag that reeled parts typically carry.