Man of Measure is a common Creature — Human Knight card from Unhinged (UNH), collector number 18. Current market price: $0.14 (foil $2.99), TCGplayer market prices via Scryfall.
As long as you're shorter than an opponent, Man of Measure gets +0/+1 and has first strike. As long as you're taller than an opponent, Man of Measure gets +1/+0.