I have heard this referred to as an old fashioned audiotape recorder, and a Reel to Reel Audio Tape Recorder. Not sure which is the proper name, but hopefully you know what they are.

Plated and enamel cufflinks.

Dimensions (LxWxH): 23mm x 23mm x 4mm (approx.)

Weight per cufflink: approx. 9.34g (average)