Abstract: A pet collar device (100) incorporates a body (117) and a reciprocating plunger (109) extending through the body. A flexible band (101), attached to one end of the plunger, extends from the body when a knob (111) of the plunger is depressed by a palm or thumb of a hand and the fingers of the same hand engage finger grips (123) on the body. The extended band allows placement over the head of a pet. Release of the plunger by the hand allows a bias spring (127) to bias the plunger in the opposite direction, retracting the flexible band into the body and securing the collar device about the neck of the animal. The collar device allows quick and simple one-handed engagement of the collar device on the animal.