The SMC DOT Straight Cartridge is a push to connect replacement unit. If the PTC ports on your Air Lift or AccuAir manifold happen to be leaking (and the air line going into them is cut at a perfect 90° angle), the o-ring inside of the port has most likely been damaged and will need to be replaced.
Replace at your own risk. We recommend having these replaced by a professional. Any replacement will void your manifold warranty.