I bought one of these at Meijer last night. Its basically a kit with a vacuum pump and three quart sized zip bags. There is a little fitting similar to the vacuum seal on a bag of coffee beans on the bag. You press the vacuum pump to the bag and run the pump until the air is sucked out.
vacuum sealed an apple. it held tight all night
vacuum sealed my xd9 sc, rear sight tore a hole in the bag
for $10 its useful for some stuff, especially small portions of food, and its easily resealable and re-vacuumable. But sharp stuff will probably destroy the bag
They have packages of quart and gallon sized bags available to buy as well.