look all the way down, i forgot the bookmark in the link.
"The RC2 microcooler is an integral Stirling engine with the detector directly mounted to the cold finger. Its 3.5 watt power requirement makes it ideal for use with a battery. Judson recommends rotary coolers when low power dissipation and portability are important. The RC2 microcooler fits easily in the palm of the hand and cools down to 77° Kelvin ± 0.5°K. "
