OLD Stronglights used a 16mm crankbolt, but these look like newer models that might have used standard 15mm (and also MIGHT be threaded to use the standard 22mm crank puller, if you're lucky), either way, the BOLT threading is the same, I believe, so you can try the 15mm and if they thread in, use 'em. I always put a little blue locktite on the threads when I install crank bolts: keeps them locked and prevents rust, too. Hope you have the chainring(s) for that crank, cause I'm guessing that the 3-hole style ain't gonna be easy to find replacements for! If you're really lucky it'll turn out to be the same BCD as all the steel cottered cranks that used 3 bolts, so you'll have a load of choices for STEEL rings...