They'll probably work, but keep in mind that they are made for handling speaker wire, which is usually 18 ga, but sometimes 16, and even potentially 14 ga. stranded wire*. To handle that size of wire, the openings are pretty big. The clamps will likely snap down onto the cap's lead with enough pressure to keep the cap in place, but if there's any looseness at all, you could experience undesirable/unpredictable results.
Otherwise, if the price is right....
* In many if not most home stereo setups (up to say 150 to 200 watts per channel), 18 ga. stranded is sufficient. Well, I'd better qualify that that with: for runs up to 100 feet or so. Longer than that, I'd advise 16 ga. for higher wattages. But the spring clamps you've shown us are not very small, so I'm betting that the manufacturer is "covering the bases" by making them capable of pulling duty in "live sound stage" situations. There, 16 ga. is considered the minimum, and 14 ga. speaker wire is often the norm. More than handling power requirements, this also encompasses ruggedness, meaning that the cable(s) have to stand up to a lot of rough handling, and small wire simply won't live very long under these conditions.
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