As someone who deals with CBP on a continuous basis (at least US CBP), it behooves you to be as explicit as possible in customs declaration forms. Identifying stuff as simply parts or used parts or valves or some other vague description only invites problems. Remember, if you're shipping stuff to the USA, under a certain threshold (I can't remember if its $250 or $500), there are no duties on goods. Even if the value is above the reporting threshold, the duty elimination provisions on goods are such that most any piece of amateur radio gear or components are duty free (regardless of value).
Being cute with Customs only invites trouble.
-----> I. Drink. Your. Milkshake!