Features and Benefit: Use with 901 or 2992 air hold fittings to keep valve closed. Length: 12-1/2". Made of quality construction for strength and durability Make the job of replacing valve springs easier with this tool. This heavy duty tool replaces weak or broken valve springs and guide seals with cylinder head on the engine. It's simple to use, just remove the rocker and fastening tool to stud with nut. Pull on handle to compress spring. It's a time saver!