I realize I should be smarter than the equipment... but for the second time in 18 years I've left the hose attached to the frost-free hose bibb (leaving water in the downstream part of the bibb), and when we had a hard freeze, the bibb ruptured - soaking the house when I turned on the hose.
Last time, I bought a device that screwed onto the hose bibb, and the hose then screwed onto the device. It was brass, and had an automatic relief valve of some sort. When the water was turned on, it passed into the hose - but when the water was turned off, the water left in the barrel of the hose bibb (downstream of the valve) automatically drained through slots in the circumference of the device, preventing freezing of the "frost-free" bibb. No manual adjustment was required each time. Of course, when I moved I left it behind.
Does anyone know what this device is, and where to find it?