The Singularity Computers Protium Quad Port reservoir cap for all Protium reservoirs. This version has 4 ports which can be used as inlets or for accessories. This cap can also be moved to the bottom of your reservoir and you can use the ports as inlets or outlets. The extra ports and 90 degree ports allow a large variety of options to reduce fittings and to make building your loop easier. An inlet tube is recommended on all reservoir caps.