We have never sold a relay like this. It is a CL-1A81-4-10 by Meder and it can operate on coil voltages less than 0.5VDC. Its known as a current sense type and has a 4 Ohm coil and SPST normally open contacts rated 0.5Amp switching and 1Amp carry at 90 volts. A 0.5V output small solar cell operates this relay-it is AMAZING! Size about 1.13" long x 0.50" x 0.41" tall. Brand new. Retails for $10.50.
Sold in a package of 5.