I can safely say that these bats will be the easiest thing you've ever painted. I spent more time on the base than on the bats!
You can buy these bats in their own pack, or the manufacturer offers them in a number of different army packs. They are nominally 15mm scale (as big bats), but to my eye look fine in 28mm scale as ordinary dungeon bats as well.
A bat consists of a single casting, comprising a round base, a vertical shaft, and the bat on top. Mine arrived in the mail totally squished, but to my surprise, the metal was resilient and I could straighten everything back out. (More or less... I never quite got the vertical shafts straight...)
How did I paint them? Dead easy. First I mounted them on steel squares, and covered the base with Renaissance Ink medium flocking gel. Then I spray painted the bats black. The "ground" got my usual three shades of gray drybrushed on, followed by an ink wash. I touched up the shaft and the bottom of the bat (hard to spray) with black, then drybrushed the top of the bat with gray. Spray with sealer, and done!
The bats have a wingspan of 7mm, and are 14mm tall from bottom of the base to top of their wings.
The bats are part of Alternative Armies' 15mm scale Hordes of Things (HOT) line.