Solid and :The Extra add tensile strength makes the spring is pretty stiff allowing for a strong seal. The posts, poppets and springs are made of stainless steel 304 for proper sanitation and unmatched durability. No Gas Leaks:The ball lock keg posts each wears a food grade standard size o-ring to prevent leakage of the connection between the ball lock and the ball lock keg posts; The Poppet valve each on the ball lock keg posts also has a standard size food grade o-rings to prevent leakage of the Poppet valve. Using the ball lock keg posts to convert a pin lock perfectly into ball lock. Standard SIZE:The ball lock keg posts have a standard 19/32inch -18 thread size. Standard corny keg posts are 7/8inch star on The gas inlet and 7/8inch Hex on the liquid outlet. These are both 11/16inch Hex. Make sure you put with the horizontal grooves on the gas inlet side. Standard Ball lock keg posts make your installation and use easier than ever.