earlvb

http://www.echobike.com

Since we can't see it we can't say for sure, but I think Try-All only made thread on fixed hubs for mod. Look at their web site to see if they made one to take a cassette cog. Most mod fixed rear hubs are thread on.

The lockrings are left-hand thread so they tighten counterclockwise. (At least on Eno and Shimano, never worked on a Tensile but I imagine it's the same.)