Silverlight key (Sir Prysin)

Silverlight key is one of the three keys needed to unlock Silverlight from its sealed casing during the Demon Slayer quest. During the start of the quest the player learns that Sir Prysin dropped his key down a drain. Using a Bucket of water on the drain outside of the kitchen will make the key fall down into Varrock Sewers.

This key unlike the other Silverlight keys is rusted, most likely due to it being stuck in the drain for a long time.