The lengths as measured are:
Atlas: 7" closed and 10" fully extended.
Harris: 8" closed and 12" extended.
The atlas allows for a lower position as the way the Harris mounts sits it up higher, my center of bore measures 8" with the Atlas while the Harris is 9.5"
Here are a few more pics showing them both collapsed and extended of a couple of my rifles.
Also, Atlas makes leg extensions that can be added and I've ordered a couple 2" extensions with my second bipod and I'm hoping it arrives some time soon!
Another feature to mention is the swivel pan action on the Atlas can be controlled with a tension nut....it's basically got a ball head that allows for vertical and horizontal movement.