any clue what this is for?

[swervncarz]

I bought out a box of tools. I found these 2 pieces together in a little box. No markings, i have no idea what they are for. I'm only assuming that they go together because they were stored together. The bigger piece is 5" long

[wvtools]

Your pictures are too dark to tell what the top item is.  The bottom item is a toolmaker's knife-edge straight edge.  It is probably a Brown & Sharpe No. 530.  They came in lengths of 2 1/4, 3 1/4, 4 1/2 and 6 1/4 inches.

[swervncarz]

Thanks, looks like you are correct. Here's a better pic of the other piece as well

[leg17]

Looks like a boring bar holder.
For clamping a round bar in a square lathe tool holder.