To collect spilled mercury quickly, unscrew the lid with the foam pad and press it firmly onto the spill. This pressure forces the mercury into the pad. When the lid is screwed back onto the jar, the pad is compressed against the jar's free-standing perforated plate, releasing the mercury into the jar bottom. 105 x 48mm O.D. (4-1/8" x 1.9") high. Foam pad is replaceable. 12 per case.