They're hidden under the "advanced" button when placing a stop-loss order. GDAX (the exchange side of Coinbase) actually have quite a plethora of order types...

They're hidden under the "advanced" button when placing a stop-loss order. GDAX (the exchange side of Coinbase) actually have quite a plethora of order types... though they don't seem to let you change the time in force for the resulting limit order when the stop-loss triggers, for whatever reason.