These well chambers are large enough to fit into a slide projector but are thin enough to view using a compound microscope. Adding a few drops of pond water to the slide gives students the ability to view a variety of life in a natural environment, rather than squeezed under a cover slip. Made of plastic with tight-fitting lids, the well chambers are durable and reusable with no sharp edges. Chamber itself is 23 mm in diameter and holds a milliliter of water. Entire unit measures 5 cm square. Package of 5.