2D Game - Get collider name

Hello everybody!
I want to create a 2D platform game, but I have a little problem …
I’ve put names for all my platforms : “platform0”, “platform1”, … but in the function OnCollisionEnter2D, using collider.gameObject.name, I can’t get the name of the platform, but I get “Collider”, “Slider”, …

How to fix it ?

(sorry for my bad english ^^)

Someone can help me ?