Kraken Bond Expanding Foam Post Hole Filler - (1x10.5 + 1x13.2 oz) 2 Part Expanding Polyurethane Concrete Alternative for Fence, Deck, Mailbox, Anchor, Waterproof Fence Post Repair Kit, 1 Pack

Works exactly as advertised

Just ordered more. 36 4x4x6 posts done so far. Used in large temperature swing from 80 down to 42 degrees. At 80 degrees foam mixed in under 1 minute and filled holes about 85%. Drilled 8” holes 2’ deep. At 42 degrees foam took 3-5 minutes to work. And only filled 75% of the hole. Kept foam at 70 degrees before using at lower temps. Posts have been solid. Even after several days of heavy rain, the posts are just as solid as when first set. Is so much easier, faster, and lighter than concrete.

It solidifies. But it activates so quickly that it’s all over the driveway rather than around the mailbox

worked as stated. did exactly what it said it would do. lil pricey compared to concrete but no clean up & easy to use

My wife and I were setting our mailbox post, I held the box while she mixed and poured this product. At first I thought I had wasted my money because nothing happened. Then a boiling began in that post hole and BOOM! It foamed up out of that hole the size of a soccer ball and hardened almost instantly. Do I recommend it? ABSOLUTELY