adamantine manacles of draining

When you put these adamantine manacles on a creature they behave like normal manacles except for the fact they grow or shrink to fit any size of creature but the real magic happens when the prisoner tries to escape. If the creature tries to escape and they fail they gain one level of exhaustion and the DC to remove the manacles raises by two.( It is originaly 20) 

Note: The exhaustion can only be removed when the manacles are removed.

Note: If they are broken they reform after 24 hours the broken pieces knitting back together.

Note: The locks cannot be picked they are opened by a command word chosen by the DM.