A 1:1 "micro" Balun for use on HF (best suited for 7-30MHz) for when you're out portable or need a low-impact balun solution. Although small, it's light enough to mount on a fishing-pole but still able to operate at up to 100w under most conditions. Can also be used with a Doublet or G5RV at the ladder-line/coax junction. All fixings are stainless-steel.
2nd picture shows a version with the terminals at the top of the box with an Elecraft KX3 for scale - yes, the box is small!