Robinair (64240) Enviro-Guard Hose Set for R-134a - 240", Set of 2 Enviro-Guard automotive A/C service hoses feature a special barrier material that prevents virtually any permeation of refrigerant yet still remains flexible These 20 foot long, 1/4 inch blue and red hoses are clearly marked for R-134a and feature a 500 PSI working pressure and 2500 PSI burst pressure 14 mm male x 1/2 inch ACME female fittings Hose ends feature a strong six-sided crimp that provides a secure, reliable connection between the hose and barb - even at maximum pressure Coupler nuts feature deep knurling for a positive grip that enables quick finger-tightening