Another term for dust jacket.Original dust wrappers add several hundred percent (never, never throw away a dust wrapper)....
Stamps are slammed on the title page, label pockets gummed to the rear pastedown, dust wrappers discarded, covers vulcanised in plastic - or, in those days, a toffee-brown buckram tough enough to withstand acid.
Some dealers also grade the books and the dust wrappers separately; this, too, is acceptable practice.