Should you experience a rip/tear or hole in your air 4mm air line, you can use this coupler simply to cut out the affected area and replace it with this.
This kit contains around 30cm of quality, flexible 4mm air line suitable for automotive use - and 2x 4mm to 4mm couplers so that you can simply splice in this section of cable - or extend a hose which is not long enough.
We also offer this in a 6mm version.