According to my Google Search, the Egyptian Ankh is the key of life. As the remains within do not appear to be wrapped or mummified, I am struggling to see the link - but there you go.
The lid of the coffin or sarcophagus opens on a hinge with the other side held in place with a tiny magnet, so it shouldn't swing on the sleeve. Bet Howard Carter would have appreciated that on the real thing.
Dimensions (LxWxH): 22mm x 16mm x 8mm (approx.)
Weight per cufflink: approx. 9g (average)
Size = x mm (W x H)