Chain Shackles

When you cast this spell, you target a creature. This target rolls a dexterity saving throw against your spell save DC. If the target is not successed the saving throw it takes 2d6 bludgeoning damage and it is binded by the chains. For a successful saving throw, target takes half damage and it do not be binded. 

If a creature binded by the chain, this creature can roll strength saving throws at each turn of it to escape the chain, the save DC of chain is related to material of the chain. While the creature is binded, this creature is grappled

But as an exception, If creature's size is higher than large, there is no grappled condition.