Allthough that looks like a good site I’ve never even seen one of those and it out if all honesty looks like one if those scam type equiptment things.
Arm band exercises strengthen the muscles that stabilize and decelerate your arm—the ones you “throw out” when you don’t warm up first.
His particular arm bands look real handy and I might buy em for $15 or so. The rest looks like the knowledge you pay for. Maybe he has some innovative ideas but you could get by with a band from the store and learn dozens of exercises free on the internet.
Every pitcher on my high school team has it (got the booster club to subsidize it) and we do variations of the exercises every-other day.
My son loves them. We have the Oates Specialties version but they look identical. We often do the drills while holding a baseball or weighted ball.