The Opticonn OTR-4U-C is a cost effective, 16 slot, 4U chassis for mounting any single or double slot OTR-30x transmitter or receiver in a equipment rack. Clean up the installation by racking up to 16 single or 8 double slot OTR-30x transmitters or receivers or mix and match in the same chassis. The unit comes standard with redundant 110-240 VAC power supplies and the OTR-30x insert cards are hot-swappable. The OTR-4U-C also has quite fans for proper air flow over the OTR-30x insert cards.