EKWB EK-RES X3 150 Water Cooling Reservoir Easier-than-ever mounting, filling and quickest bleeding of air. Reservoir is manufactured of premium quality 60mm acrylic tube and POM Acetal end caps. The sealing is performed by quality EPDM rubber washers. New RES X3 comes with a pair of EK design reservoir holders using adjustable fastening force controlled by enclosed Allen key.