Rainbird Mini Root Watering System with 1402 Bubbler on Riser Grate and Spiral Barb Elbow, 4"/0.5" RWS-Mini Root Watering System with 18 in. Tube, 0.5 GPM Bubbler & Check Valve, 4 in. Grate Factory installed 1/2 in. (1.3 cm) spiral barb elbow with 1402 bubbler makes connecting to lateral lines easy Check valve - Minimizes transplant shock - Directs water to root ball and adjacent soil Supplements top-down soaking - Quicker tree and shrub growth - Provide a stable foundation against high winds Reduces waste due to run-off - Minimizes evaporation - Grate collar has an integrated clip for 1/4 in. (0.6 cm) tubing