The red “cans” under out jacks in some of our videos are Andersen Jack Blocks. We don't use them anymore because we've broken NINE of them (6 we bought and 4 replacements they sent us). Simply unreliable. The bottom edge would break off and they'd sink into the gravel / dirt / whatever.
We've switched to RV SnapPads and love them. They don't help lessen the jack extension like the Jack Blocks did, but they don't break and they stay on the rig, which is great when setting up and breaking down camp.
Note: The same company (RVSnapPad) is going to be coming out with a new product that will integrate with the SnapPads to help with the jack extension / stability this year. We will be helping them prototype those and will do do a video on them when they come out.