A Stop Limit Order is almost identical to the Stop Order, with one key difference. A trader can specify the lowest price below the stop price that you’re willing to sell at. This is typically done when a trader needs a precise price, or to prevent selling in a free fall.
A trader holds a Bitcoin with book value of $10,000 and wants to sell if the price drops below $9,000, but not if it drops below $8,900. The order will only fill in that $8,900 - $9,000 range. If only a Stop Order is used, other orders may be filled before the traders specific order and by the time it does fill, the price may fall to $5,000 (as an example).
With the Stop Limit Order the order would not have filled and the Bitcoin stays whole.