TOWA isn't an acronim, it's the company name. Towa makes lots of products. Here is the tension gauge, you can get it for a few different bobbin sizes.
http://www.superiorthreads.com/shop/...FQ8zaQodZxwJWg
I've considered getting one, but after I updated the tension on the long arm, I'm not having near the problems. However I'd love to hear how it's working.