PLASTIMO Flexible, light and form-fitting, these tanks use a PVC bladder inside a tough, abrasion-resistant nylon outer envelope. Maintenance is easy because the inner bladder can be removed for cleaning and inspection. The bladder is slightly oversized so pressure is exerted on its nylon shell, rather than on the heat-welded seams. Port Sizes Fittings: Inlet 1 1/2" 90deg fill (38 mm) situated on upper side of tank. Outlet: 1/2" straight fittings (12 mm) valve is situated on underneath side of tank. (except on triangular model : inlet and outlet are both on upper side of tank). Vent: No. Fitting Type: 90 deg hose barb rotates 360deg. Height of tanks, when filled to capacity : 25 cm.