Lactina Double Pumping System. This kit contains everything you need to single or double pump (that is pump one or both breasts at the same time) with the Lactina breast pump. -- The Lactina Kit contains one pair PersonalFit breastshields (size medium 24mm), one pair PersonalFit connectors, two yellow valves and white membranes, two five ounce collection bottles with solid yellow lids (BPA free), two pump tubes, one pump connector, piston, and cylinder assembly (that attaches to the front of the Lactina pump), one bottle stand, and two spare white membranes, plus Lactina instruction book. All listed parts are also available for purchase as separate items.