With rounded edges and polished surfaces, these spring plungers are free of nooks and crannies where dirt, water, and bacteria could collect. The seal on the base keeps contaminants off the threads and is bright blue, so you can easily spot broken pieces that fall into your line. A tug of the knob manually retracts the nose so you can do everything from positioning containers on an assembly line to locking mixing blades in place. Spring plungers are FDA compliant for direct contact with food.