Put two seals on flat, parallel surfaces. They generate a 4 m x 4 m invisible wall of invulnerable force between them. The wall can easily be jumped over or gone around if you know it’s there, but it’s ridiculously thin; running into it tends to cut you in half. It lasts for 12 hours or until the seals are damaged (the seals can be damaged from both sides of the barrier) or moved. If you have the tags prepared it takes about a minute to get them set up and activated. Attempting to create a wall when there is anything solid in the way causes the seals to fail and be ruined.

Additional info in eaglejarl’s post (#17981) re: VHiLEO ascent vehicle

“The seals that generate it are not inherently fixed in place. They need to be anchored to something, and they need careful alignment in order to function. If either one is moved even slightly the wall will fail.
The wall needs to form in clear space. Any significant solid or liquid in between the seals will cause the wall to not form. The GMs are discussing what the appropriate limits on this are. So far we know that smoke won't interfere but dust / bugs might given sufficient density. Suggestions about appropriate units for this are welcome.
The edge of the wall is extremely thin and tends to cut through things that encounter it. Things like ropes, poles, and shins. It isn't completely 2D, so it is *possible* to rest something against it, but it is highly contraindicated.
The wall is invisible, so knowing where it is is non-trivial. Stepping up on a horizontal wall is definitely doable, but you want to be careful. Climbing up on it (i.e. gripping and pulling yourself up) will cost you your fingers.
The wall isn't frictionless. It's about like modern glass as far as smoothness goes.
In theory you could form an air- or watertight seal between two force walls. In practice you can't because you can't align the seals closely enough.”