I have Run these glow plugs in my O.S. 21 outboard engine and went through 2 in throught the whole season without babying the motor. I have also run them in my OPS 45 and have gone through many plugs ranging from MCcoy plugs to O.S. plugs and burn't them all up as soon as the engine shut down. I really think I have a small problem with my engine and not the plugs.
On a better note!!! The plugs are my favorite so far in my 2 boats that I have run them in so far!!!
You can get show specials at the Toledo and Chicago show, as far as I know of. There they run about $4.00 per plug, which I think is still a GREAT deal.