The LNF-ISISISC4.3_4.9A from Low Noise Factory is a Cryogenic Triple Junction Isolator that operates from 4.3 to 4.9 GHz. It has an insertion loss of 0.4 dB (at 5 K) and provides 70 dB of isolation. This circulator has been designed from the ground up to meet the strict requirements of ultra-low temperature physics research. The gold-plated OFHC copper body ensures minimum loss, and that this loss reaches the lowest possible temperature to minimize thermal noise. It is available in a module that measures 67.06 x 24.64 x 10.16 mm and has SMA-female connectors.