Compatible with American Maid plastic water bottles and water jugs that have a 53-400 threaded neck finish. Included: 53mm (53-400) size screw-on caps with foam liner, 3-pk.Not compatible with water jug brands such as such as: Bluewave, New Wave Enviro, PureAqua Jugs, and Ore International, which instead require a 48mm sized cap. Not for use on water dispenser bottles that require snap on caps; not for use on glass jugs.Caps feature a 3-ply compressible foam liner. BPA free. Made in the USA. Cap is not designed to be leakproof.Note: it is difficult to determine the cap size from the jug’s brand, as some have changed their bottle design over the years. And the jug's gallon size does not determine the cap size.To find the right cap size for your bottle, the easiest and most reliable method is to simply measure the OD (outer diameter) of your old caps. The 53mm size caps have an OD of about 2-3/16”. Or, check the water jug's label, as it may also specify which cap size is needed. Dimensions of 53mm size cap: Inner Diameter: 53mm (2.09 inches), Outer Diameter: 55mm (2.17 inches). 53mm cap for use on models such as: American Maid. Please note that these caps aren't universal, as there are many other cap sizes available. Each water bottle brand has it's own neck design, and therefore requires a specific cap size based on the width of the neck and closure type (screw-on or snap-on). For example, the 53mm sized screw-on cap fits the 1, 2, 3, and 5 gallon American Maid brand bottles. And the 48mm sized screw-on cap generally fits on the 1, 2, 3, and 5 gallon Bluewave, New Wave Enviro, PureAqua, H8O, and LavoHome brand bottles. These do not fit on bottles that require Snap-On caps (where the bottle's lip is rounded and has no thread). Brands that typically require Snap-On caps: Nestle, Primo, Zephyrhills, Crystal Springs, Poland Spring, Arrowhead, Deer Park, Ozarka, Pure Life, Brio, Polar Arctic, and Clack brand bottles. These do not fit on glass bottles.