Grey Clone-Brand Brick With a Single Short Tube on the Bottom? I've had this brick for a while, and I've long wondered what it is.

It's a LEGO-compatible 2x4 brick, colored almost exactly the same as the old medium grey. There are no identifying marking, and the only marking of any kind is a single line on the bottom, which I assume is a 1.

The most distinguishing feature is that it has only 1 tube on the bottom, and it doesn't reach all the way down.

I originally found it in a bucket of otherwise genuine LEGO pieces years back, so no clues there.





I'm quite certain it's not a genuine LEGO piece, but it is an odd piece and I've long wondered what it's from?
As luck would have it I stumbled upon your answer today sorting through my own mess. It's a Tyco brick. Although the picture doesn't show it, the one I have has a white sticker with the word "DANGER" in red on one side. Hope someone finds this useful.