The question behind this search is usually: how do I bridge three days of refrigerated transport. The honest answer is that no gel pack does that on its own. The combination of insulation, cooling mass and preparation determines whether you reach 72 hours.
What makes 72 hours possible
Three things at once: a thick-walled polystyrene box, enough cooling mass in proportion to the contents, and products that go into the box already at temperature. If one of the three is missing, you will not make it, no matter which pack you choose.
Cooling mass
Heavier packs contain more cooling mass and last longer. For long journeys, you are therefore better off with a few heavy packs than with many light ones. Spread them around the box instead of piling them up, and keep the top free for the largest share.
Freeze solid all the way through
This is where things most often go wrong in practice. A pack frozen in a stack feels hard but is still liquid inside, and then delivers a fraction of the expected cooling time. Freeze flat, separately, and for at least 24 hours at minus 18 degrees.
Box and fill level
Thick-walled EPS doubles the cooling time compared with thin-walled. A full box holds its temperature considerably longer than a half-full one: air is the space in which heat circulates.
Plan for your longest scenario
Three days on paper can become four with a delay. Build in a margin, because temperature damage cannot be undone.
Test your own route
Every route is different. If you want certainty, send a trial shipment with a data logger. That is the only way to know what your combination really does.