The problem with most available "hollowing" tools is that the cutting edge is not on center, which will cause them to grab and catch, they are the wrong shape, or simply too big to fit into small opening hollow turnings. Tool companies or people who don't actually use the tools usually produce them, and they don't really understand the concepts. I have spent many years being frustrated over students having to modify existing tools, hand make tools, or just using something not really suitable.
Not being able to find anyone to make them reliably, I have invested in the equipment necessary to make these tools, so that Vicki and I can produce them ourselves. The hook tools are exact copies of the hook tools I have used for over 20 years (with a better finish!)
The hook tool comes in two sizes: the #1 hook is for most hollow turning and the #2 hook will reach further into large pieces when needed. They may be used in a variety of handles - I usually use the armbrace style handle. They also work well with the captured boring handles.
The tools come in 3 sizes - 3/4", 1/2" and 3/8" in diameter and come with 3/16" HSS removable tips, which are easily sharpened with the sharpening jig or by hand. The #1 hook is approx. 16" long and the #2 hook and straight tool are each approximately 20" long. Half inch tools are approximately 12" long and the 3/8" tools are approximately 10" long. All of the tools have a black oxide finish. These are the best hook tools available for doing small opening hollow turnings - period. If you don't think so, I'll refund your money.