R-134a Recharge Hose Adapter allows the safe use of older, piercing style, A/C recharge hoses with R-134a cans that are fitted with self-sealing valves. Simply screw on the adapter to the can and then screw the hose onto the adapter and you're ready to start the regular recharge instructions found on your can of R-134a. Note: this product is not for use with R-134a cans that require piercing.