You may or may not know the proper fit of a clamp, so we are here to help. Don't have a leak - make sure you use the right clamps. The right clamp depends on the outside diameter of the tubing and the material type. Since tubing is most often described with inside diameter and material, we have made descriptions on the clamps for you. You can also go by the outside diameter which is best to go off of this chart.
These are Oetiker clamps. If you need an Oetiker Crimp tool, we will have that posted very soon.