Shredders range in size and price from small and inexpensive units designed for a certain amount of pages, to large units used by commercial shredding services that cost hundreds of thousands of dollars and can shred millions of documents per hour. Some shredders used by a commercial shredding service are built into a shredding truck.
The general small shredder is an electrically powered device, but there some that are manually powered, such as special scissors with multiple blade pairs and hand-cranked rotary shredders.
These machines are classified according to the size and shape of the shreds they produce. (As a practical matter, this is also a measure of the degree of randomness or entropy they conduct.) All types of shredders can range in size from standard scissors and other hand-operated devices all the way up to truck-sized shredders. There are also shredder selector sites that can help consumers choose a shredder that is appropriate for their needs.