12 Ez Cap Flip Top Stopper Root O-ring Type Beer Bottles Replacement Swing Tops Homebrew Brewing Design that inserts into the top of your bottle to create an instant airtight seal.It's better than ordinary EZ cap, Steel ring install on bottle, More stable.VMatching pad and nuts included, Easy for use. 12 pcs swing cap package, For inner diameter 17mm bottle. The clamp ring inner diameter: 27mm Cap Top Diameter: 1 in (2.5 cm),Cap Height: 0.84 in (2.1 cm),Cap Bottom Diameter: 0.54 in (1.4 cm) Rubber Gasket Inside Diameter: 0.4 in (1 cm),Rubber Gasket Outside Diameter: 0.96 in (2.4 cm) (when not installed on the cap) Metal Wire Diameter: 0.12 in (3 mm)