one stop outdoor 20-pack - irrigation fittings coupling for 1/2" drip tubing - barbed connectors (fits most brands, rain bird 16mm .520 id and compatible drip or sprinkler systems) (coupling 20-pack) one stop outdoor every drip irrigation system depends on reliable, leak-free connection fittings to keep the system together. your 20-piece couplings - (create two way connections of poly tubing or dripline). product specifications: for connecting emitterline and polyethylene tubing use with 16mm emitterline and distribution tubing. one piece construction uv resistant high impact plastic secure and easy installation without glue or clamps operating pressure: up to 30 psi installation tips: push the tubing as far ver the barbed ends as possible. it should be a very secure fit. it should be nearly impossible (relatively speaking) to pull the tubing back off by hand. it is recommended to let the tubing heat up in the sun before installation to soften and make it more maneuverable. if your system runs at a high psi (over 25psi) you may want to consider regulating pressure or using clamps over the fittings to be sure you will not have any blow outs or leaking issues.