Ah, the benefits of copy-and-pasting:

Try Gyminthepocket.

I bought the green one, which has the hardest resistance. It works like a charm when doing stretching exercises or when you're on the road with no access to a gym and you would like to get some exercise done.

You can find it at any Fitness Concept stores. They retail from RM60 to about RM90 IIRC.