Stem Assembly Replacement 10'' Brass For Frost Free Sillcock, Proline #888-563 The search results for "Proline #888-563" indicate the user is looking for a replacement plumbing part. The number refers to a ProLine or B K 10-inch replacement stem assembly for a frost-free sillcock (hose bib). The stem assembly, with an overall length of 13.5 inches, provides water flow control inside the spigot. Here are the key details about ProLine #888-563: Product Name: 10-inch Replacement Stem Assembly. Purpose: For anti-siphon, frost-free sillcocks (outdoor faucets). Function: Controls the water flow inside the sillcock. Stem Length: 10 inches (the portion behind the wall). Overall Length: 13.5 inches. Material: Typically brass construction. Compatibility: Fits 10-inch ProLine series frost-free sillcocks. B K is also a related brand. How to measure To ensure you buy the correct replacement, measure your existing sillcock: Measure the stem length behind the wall: Do not include the threads and sillcock itself. Match the length: Use this measurement to confirm you need the 10-inch version