541385 Robinair 9 Foot Enviro-Guard Low Side Hose For 34788 34288 34134Z Units. Enviro-Guard Hoses for Automotive R-134a. Enviro-Guard Hoses are constructed of special barrier material which prevent virtually any permeation of refrigerant, yet remains flexible. Meet all specifications for low permeation construction. Clearly marked for R-134a. 740 psi working pressure, 3700 psi burst pressure. Fittings are 7/16" Flare x 14MM Hose for Automotive R-134a.