These metal restraints can bind a Small or Medium creature. Escaping the manacles requires a successful DC 20 Dexterity check. Breaking them requires a successful DC 20 Strength check. Each set of manacles comes with one key. Without the key, a creature proficient with thieves’ tools can pick the manacles’ lock with a successful DC 15 Dexterity check. Manacles have 15 hit points.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.