When you have a capo-ble banjo, you will want a capo. In general, banjo capos don’t fit any banjo above the 4th fret. One does: the Paige wide profile banjo capo. The “clik” version has a superior mechanism, and allows for a somewhat thicker neck.
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Other capos can be modified. You can shorten most guitar capos with your trusty hacksaw, and file down the resulting rough edge. As always, be sure to buy the correct profile: flat or radiused. And try it out before you saw a piece off of it.