Review on Factory Spec 12 115 Spark Plug by Mark Saric

Handle replacement spark plugs cleanly/safely. Now for the bad: For more than 20 years these holders have had 3 mounting holes in the right place. The mounting hole on the 4th/end is too close to the end of the holder and won't allow a 3/16" rivet in that hole! rivet flange on one side, with wire cutter; Then put a small nut on the rivet shank to lift the jaw of the rivet gun away from the plastic holder before pushing the rivet out / unless you make some modifications like this; You risk breaking the end of the plastic spark plug holder.) I still use these spark plug holders and they are particularly handy as I can carry spare plugs, numbered for each cylinder, without mixing them up!