RT4 multi-function trailer valve. Used on trailers to control both parking and emergency brake functions. Controls reservoir charging, applies emergency (parking) brakes upon loss of supply (emergency) line pressure. Meets all FMVSS-121 trailer requirements for spring brake control and other regulations from October 1992 to present. Interchangeable with competitive units.

• 3/8" trailer supply port, 3/8" trailer control port
• (1) 1/2" and (1) 3/8" reservoir ports
• (4) 3/8" delivery ports
• 70 PSI ppv closing pressure