These are crystal clear acrylic containers that are thin, thin, thin!  So they're great to add to cards, books, boxes, even scrapbooks.  Each comes in two pieces which snap together to form an airtight container.  Be careful before snapping them together because the seal is very tight and they are difficult to get apart once snapped together! Large, round and rectangular come in sets of six tops and bottoms.

Large, round: o.d is 1.75, id = 1.6, depth is .125