The HypaFOX LI Monitoring Cassettes, is a low profile plug and play cassette, fitted with low loss fully passive components. Up to four (4) HypaFOX slide-in cassettes can be housed on a 1RU 19/21" Subrack/Patch Panel. The HypaFOX LI Monitoring Cassette, enables monitoring of 4 fibre optic Singlemode data transmission channels. The LI Monitoring Cassette is fitted with 12, Low Loss Grade A LC UPC optical connectors. Two Channels inputs (_+27dBm), are being monitored using two, 1:2 split, 50/50 SM Splitter/coupler. The 50/50 Split Monitor Outputs are via a Polarization Insensitive Dual Stage Optical Isolator. The PI Dual Stage Optical Isolator, allows light output from the Monitor Channels and blocks any light signal entering the Monitor 50/50 split channels. Two additional channels are monitored using 1:2 split 5/95 SM Splitters/coupler. These 5% Monitor Outputs are connected directly to the LC UPC connectors.