Mansfield"s 500 series eliminates the possibility of freezing by connecting the hydrant valve to the supply piping in heated portions of the structure, providing water all year to areas prone to freezing with the added benefit of a vacuum breaker. The Mansfield 500 series stems will work for Mansfield sillcocks manufactured before 2007 and will not fit the new Diamond series sillcocks. Overall length of stem from end of cartridge to opposite end is 12". Remove existing stem from sillcock, then measure stem from end to end for accurate length. Mansfield products are now manufactured by Prier, who recommends using a self-tapping stainless steel screw to help in installation, as the replacement stem does not come tapped for the handle screw.