Stop Limit orders are used like stop orders, but execution is restricted to the limit price or better. They do not become market orders once the stop price has been reached. No order is guaranteed an execution.
Buy Stop Limit is activated when the commodity is bid or traded at or above the stop level. The order is not filled unless the price remains at or drops below the limit level.
Sell Stop Limit is activated when the commodity is offered or traded at or below the stop level, the order is not filled unless the price remains at or rises above the limit level.
Note: For CME stop orders are processed as limit orders (market with protection).