Sonic Tronics has long made some of the very best glow plugs. This model is without idle bar and long. Fits most glow engines down to around .15. Some .15 engines take a short. All .18 and up take a long. Glo-Devils are 1.5V Glow Plugs with high performance Platinum Elements designed to perform longer and better. They are available for 2 Cycle and 4 Cycle engines. Use caution on OS MAX & YS Engines as cylinder Head Damage can occur if the wrong glow plug is installed. 2 Cycle Engines.