glass, with rubber bulbs and screw-on plastic bottle top
These have many lab uses. You may purchase them separately here, or with 1/2 ounce dropper bottles (as item #1121).
Separately, these also double as Cartesian Divers in #200 Diving into Pressure & Buoyancy. If you already have droppers, test them in advance to see if they make good 'divers': Remove plastic bottle top, if any. Dropper must float when empty, then sink with a one-squeeze-intake of water. Test that the seal between bulb and barrel is water tight: The empty dropper should float for a day or so in a glass of water, without taking on visible water.
