Any of the little cheap flashlights would work for just checking veins and for some movement but if you're hoping to get a good look at pattern further into development, you'll need something with a little more oomph. The light I was using this past season was around 100 lumens, I think, and while I was able to make out some pattern and was able to ID my pied eggs before they hatched, I think the patterns would have shown up much better if I had been using a flashlight with more lumens.