Highlight the R1234YF low side: Blue is the R1234YF quick coupler on the bottom side. The R1234YF connector on the low side is 14 mm female x 1/4" male SAE. Adapter connector R12 to R134a: 1/4" SAE female x low pressure connector R134A 13 mm. R1234YF high pressure side: R1234YF high pressure side quick coupler in red: R1234YF high pressure side connector 17 mm female x 1/4" male SAE. Adapter connector R12 to R134a: 1/4" SAE female x high pressure connector R134A 16 mm. High quality material: The quick coupler is made of brass, which is strong and durable, high strength, rust resistant, not easy to break, and can be used for a long time. The ball lock design combined with the rubber seal ensures a secure seal. Wide application: This low and high side quick coupler is suitable for charging AC car air conditioner systems using R1234YF or R12 to R134A refrigerants, manifold pressure gauge setups, diagnostic inspections, recovery, and evacuation. Key features: 1. This R1234YF quick coupler fits AC charging systems for car air conditioning using R1234YF or R12 to R134A refrigerants. 2. High quality hose adapter from R1234YF to R134A with robust design for high working efficiency and long-term use. 3. Ball lock design and rubber sealing ring ensure reliable sealing when connecting R1234YF to R134A systems. Material: Brass. Size: 7.3x1.6 cm / 2.8x0.6 inch. Color: Red and Blue. Package includes: 2 pcs/set R1234YF to R134A quick couplers.