English rule for ending past participle?

The sentence Are there any good ones left is an example of a reduced relative clause.

The Oxford Dictionary of English Grammar (p353) defines a reduced clause as:

a shortened clause, particularly a non-finite or verbless clause with a postmodifying function that can be interpreted as a relative clause with its relative pronoun and finite verb omitted, e.g.

• Anyone scared of heights is advised not to attempt to climb this tower. (= Anyone who is scared of heights ...)

The general term for the omission of words that are recoverable by the listener or reader is ellipsis.

Note: Expanding the last sentence The items are eligible described below to include the pronoun and verb results in:

• The items are eligible which are described below.

The expansion is itself of dubious grammaticality. The original sentence is of certain ungrammaticality.