Cap Elevator and Bowl Feeder Systems specification should start with the real closure.
An elevator and bowl feeder combination is useful where the bowl should not be manually refilled or where line speed requires a larger cap store. The elevator keeps the bowl supplied while the bowl carries out fine orientation and discharge control.
For a better buying decision, the useful comparison is not only hopper size or headline speed. It is how the feeder behaves with your closure, how the capper receives the cap and how easy the line is to run after changeover.
The safest specification route is to start with real closures, target output, line photos and the exact point where the cap must be presented. That avoids choosing a feeder on a generic speed figure that does not match the cap or capper.