Are you building a CETME L from a kit? Do you want spares to keep your MarColMar CETME L in top condition? This is a newly manufactured mainspring developed from extensive high-speed video and photographic analysis of the CETME L action under fire. The mainspring is essential to keep the bolt and carrier properly loading from the magazine, and closing the action under fire. The spring rate has been increased to provide better functioning of the CETME L.