The RO-122 tank's water storage chamber features a virgin polypropylene liner, high-grade chlorobutyl diaphragm and stainless steel 1/4" MPT water connection. * The diaphragm is post-cured to ensure that your water is tasteless, odorless and contaminant free. * The tank is built with a sealed brass air valve and o-ring sealed cap to ensure a leak-free air chamber. Perfect for compact under sink RO units, RVs, Campers, or any other use where space is limited. * This tank discharges efficiently in a vertical or horizontal position. * Tank comes with Pre-charged pressure and ready to use. * A Fitting is required to connect to your water system and faucet