Irrigation Equipment we use

Source: Mainly Drip Depot, which is exclusively an online retailer
T connectors (called Perma-Loc Tubing Tee - Size : 3/4")
   Used to connect drip tubing from the main line (mainly for o rings that go around trees/shrubs):

Can also connect directly off the main line without a tee:

drip tubing (blue stripe Toro 1/2" drip tubing)
   Dimensions = .710 O.D. x .620 I.D (outer diameter and inner diameter)