Gem size 1.5 x 1 Civil War tintype 3 brothers Union uniforms Pennsylvania

  

Here is a gem-size tintype from the Civil War of what appears to be three young brothers, all in Union uniforms. One wears a kepi with wreath but I cannot make out the number. Composition and clarity is excellent.

Measures 1 x 1.5. Came from a Pennsylvania collection with other Pennsylvania images and a few items from the 131st P.

But I can't be sure who these gents are. Condition is superb, as shown.