Sherline 1289 Sherline Riser 3/8" Insert Holder Toolpost The rocker riser toolpost (P/N 1288) and 3/8" riser toolpost (P/N 1289) bring tools to the proper height for use with the riser block on the lathe. Each also has a 3/8" round hole for insert tool holders. The rocker toolpost allows 1/4" cutting tools to be adjusted so their cutting tip is exactly on the lathe's centerline. The 3/8" tool holder holds round or square 3/8" cutting tools, sizes most often used for carbide insert tools.