Sierra 18-99408 4 Cyl Mercury Trigger Replaces CDI 134-9021-4This Sierra power pack is for use with Mercury outboard engines.Sierra 18-99408 Trigger Application InformationThis power pack is used 80 JET, 100, 115, & 125HP Mercury Outboard engines built between 1988-1997.What is the 18-99408 Trigger Interchangeable with? CDI; 134-9021-4; Mercury; 99021A6; Click here for Sierra 18-99408 4 Cylinder Trigger Installation Instructions