• For a dry block position • Material: Brass • Includes: Retaining Ring (RPI Part #ADR240) & (2) O-Ring (RPI Part #RPO303) • Fits: Control Blocks 300 & 500 series • Model(s) This Part Fits: Cartridges, Handpiece Control Block 300 Series (38.1831.00), Handpiece Control Block 500 Series (38.1776.00)