2cm wide, 1.5cm tall. These are cufflinks designed with an NEC IC chip. I believe they are from the Showa era (1955-1975). They were originally part of a set with a tie clip, but only one cufflink remains. They are old, so there is some dirt and minor scratches. Someone else is selling these on Mercari, so you can search "NEC IC chip" on Mercari for more details. If I can combine shipping with other items, I will give this to you for free. I will ship via Yu-packet Post Mini.