Larry, I typed in Merlin glow plugs and it directed me to their site. I see they list plugs for the glo bee heads but they're currently not available. They have contact info on the site as well. I truly wish Mecoa wasn't so slow in bringing items to the table. They seem to list many products in the site and are unobtainable for years. I was comparing a few plugs the other night. I had Nelson, Norvel, Ap, Glo Bee and they all fit within the same clamp. The differences were usually within the squish area. The Glo Bee also had a finer and wider element. The ap has an area more like a stock low compression head where as the others are more like the trumpet style. I haven't done any rpm checks on each of these yet. I've been trying my hand at making a mouse racing engine. So far out of all my experiments the Galbreath head has been showing the highest rpm's. Yesterday, we tached the Black Widow at 23,800. I can't seem to keep the Nelson plug in it tight though. I think it just keeps loosening from heat. Every plug except for the Nelson has been suffering from the white deposits you had mentioned in another post. This seriously degrades performance especially when your going for the maneuvers. On another note, for those who have been trying to use Cox plugs in their Norvel watch when trying Norvel in Cox. I've discovered that the piston can hit the plug or the clamp itself. I think this is due to the narrow area a stock Cox plug has for its sealing edge to the washer. The Norvel has a lot more area there. I'm sure additional glo plug washers would help. Ken