The frog-leather body can be bought from Reldak in the market place of Dorgesh-Kaan. It can also be looted from the Dorgesh-Kaan average chests, which require 52 Thieving to unlock. This piece of armour requires 25 Defence and Ranged to wear.
The full frog-leather armour set consists of:
All Junk chance: 72.5 Junk chance: 72.5