Save both water and money: 4 packs switch valve for use with 1/2 inch drip irrigation tubing, helping your adjust water to flow or to turn off, save your money Easy to use: top red handle turns to adjust or completely shut off water, easy to operate Operation: self-piercing design use with 1/2 inch drip tubing or insert into larger drip tubing; Fits most tubing 1/2 inch: approximately. 520 - 550 ID range