[Agitator]

I've read that the reason more people don't use these is that may pedals have sides that are not exactly straight up-and-down (i.e. perpendicular to the floor). When the boxes are die-cast, it's easier to get them out of the die if they slant slightly inward from bottom to top. So if you use something like this to connect the pedals, you could be putting some pressure on the jack.

In the picture you posted, it looks like the plugs may rotate up and down a little, which would fix this problem, but if you're looking for the non-offset versions, they probably won't rotate.