ProLine Single Control for 8-In. Sillcock Value is designed specifically for use with anti-siphon, frost- sillcocks. This part is measured by the length of the stem that extends behind the wall, but keep in mind that the overall length of the valve is longer. For an accurate fit, measure from the back of the wall flange to the valve’s end, excluding the threading and sillcock portion. This ensures you select the correct valve that matches your existing sillcock’s specifications, providing reliable and efficient performance. Model Number: 888-572HC