Every fucking machine review online ranks by RPM and thrust length. Both numbers matter — but they're measuring two different sensations, and people who pick by RPM alone are the ones who end up returning.
Pressure machines (A2 / A5 class)
Shorter throw, higher tension on the hold-down. Sensation is constant fullness, very little 'arrival.' Better if you're sensitive to depth or new to penetration toys.
Depth machines (A8 / Pro class)
Longer throw, more momentum per stroke. Sensation is rhythmic, with a clear stroke top and bottom. Better if you want to feel the machine 'thrust' — closer to partner sex pacing.
The question to ask yourself
'Do I want fullness or rhythm?' — if you can't answer immediately, start with pressure. Easier to scale up to depth than scale back from it.
