Stop-limit order
A stop-limit order becomes a limit order when a stop price is reached, so it never fills below your limit but may not fill at all. Definition and example.
Definition
An order that becomes a limit order once a stop price is reached: it never sells below your limit, but in a fast fall it may not fill at all.
A stop-limit order has two prices: a stop price that triggers it and a limit price, the worst price you accept. When the market reaches the stop, a limit order at your limit price goes to the exchange. It never sells below your limit, but if the price falls through the limit before the order fills, nothing sells.
Example
You hold ETH bought at $3,000 and place a stop-limit with a stop at $2,820 and a limit at $2,800. If ETH falls gently to $2,820, the order fills at around $2,800 or better. If ETH drops from $2,815 to $2,760 in one move, the order sits unfilled at $2,800 while the price keeps falling, and you still hold the position.
Why it matters
The choice between a stop-limit and a plain stop-loss is a choice between price and certainty. A stop-limit protects the price you get and risks not selling at all. A stop-loss gets you out and risks a worse price. In a crash, a stop-limit that does not fill offers no protection.
How TradeCorgi uses it
TradeCorgi agents use a stop-loss that sells at market, because for protecting a position, getting out matters more than the exact price. Use a stop-limit when price matters more than getting out, such as on a thinly traded coin, and leave a gap between stop and limit a little wider than the coin's usual slippage.