Funny you bring these up. I bought some of these last year because Tom Boley was raving about them. When I dropped them in the hole last year all the fish I was marking scattered like they were terrified, whereas regular tungstens they would eat. I haven't used them this year because that didnt really give me much confidence in them. If you have had success on them, I should give them another shot. I think mine were the 3mm or 4mm (which is like 3-4x the size of a standard 3 or 4mm teardrop).