28mm Cap Feeders specification should start with the real closure.
28mm caps are common in beverage, chemical and personal care packaging, but the feeder still needs to be chosen around cap weight, tamper band detail and output rate. Sports caps and flip-tops may need more orientation control than plain screw caps.
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.