Cap Feeder Samples specification should start with the real closure.
Real samples reduce guesswork. Caps can differ in weight, static, moulding detail and how they sit in a bowl or chute. Photos and dimensions help, but final specification is strongest when production caps and bottle details are available.
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.