This kit includes a high (hot) and low (cold) side service couplers. They are required to connect to an automotive AC system. Although these AC service connectors look the same but their connector side are not identical. They have different inner diameter therefore they are not interchangeable. This is with reason to avoid the danger to connect them to the wrong service port. These R134a high and low side couplers are standardised connectors that you can find in cars nowadays. If you find these connectors you will most likely have an R134a AC system but you must read you owner's manual before you charge your air conditioning.  As the R134a connectors have different diameter you won't be able to connect your high size coupler to your low side port. It will not fit.

This kit includes:

*1pc of LOW side service coupler
*1pc of HIGH side service coupler