Steelbound Harness is one of a profession mounts coming in Legion. Blacksmiths can make this mount. It can be traded or be sold, it doesn't need blacksmithing skill when riding it. I believe it will be as popular as Vial of the Sands and Jeweled Onyx Panther.

With the opening of Nighthold, this mount has begun to appear in our line of sight. 
The recipe is dropped by Tichondrius in the normal Nighthold, but it requires Blacksmithing level 800.
Players just can learn this recipe after you defeated the boss Tichondrius. You can earn much more wow gold if you can get the recipe earlier.
The shape of this mount looks like Core Hound Harness in MC. It is Peculiar only if compared with Core Hound Harness since it's color can be changed into green. 
If you miss the tenth anniversary of World of Warcraft, Steelbound Harness is a nice choice, it may be can make up for the regret.