Rings.

Two rings. The whole upper body.

Birch rings are the most uncompromising upper body equipment there is: dips, rows, muscle-ups and holds, where your body has to stabilise everything a machine would otherwise lock for you. The grip is 32 mm wood that holds chalk well, and the straps are numbered, so both rings hang at exactly the same height without measuring. Straps in 2.8 or 5 metres. Unstable equipment, stable shoulders.