Ameda Breast Milk Storage Bottles with Lock-Tight Caps, 4 oz, 4-Pack.Four 4 oz polypropylene breast milk storage bottles with two-piece locking rings and discs. Universal threading is compatible with Ameda HygieniKit Milk Collection Systems, all Ameda breast pumps except Ameda Mya, and most standard-thread breast pumps. BPA- and DEHP-free; dishwasher and freezer safe.