Sweep routers are used to maximize the available size (whether the blocks are being bought or sold) by splitting large blocks into smaller ones and the simultaneosly routing to the different exchanges. So, rather than sending an order for one large block or puts or calls to one exchange, the order is split and routed electronically to multiple options exchanges.

http://whatstrading.com/2009/04/28/options-101-where-do-options-trade/

Thank you