Hi Ed Greenburg,

A slip rail is a type of fence system where there are two open brackets on the fence posts on either side of a farm gateway. There is a long, heavy rail or piece of square or rectangle ended wood inserted into the brackets on either side so that the rail could be slipped or slid to the side to allow access through the gateway, and then slipped back to close the gateway.

If you do an image search for slip rail you can see how it works. It's a clever, simple concept, but a little difficult to describe simply. It takes the place of a swinging gate and is very secure when keeping in farm animals, e.g. horses etc.

Helen, in Australia