Spotted this on Keepa, $3.93, down from $7.99.
Quick Connect Hozelock AquaStop Fitting for 12.5mm & 15mm hose, this fitting is best used at the gun end of a hosepipe.
An internal valve stops the water flow when an accessory (e.g. a spraygun) is disconnected
Edit: Should be eligible for cashback as it's in Garden category.