As a couple of the posters indicated, the Montanas come with the optional hydralic valve selector switches to control how many slides you wish to open/close. I can access my entire unit by just walking through since they just started making the 3500RL model with sliding rear den doors. Even though I purchased the optional selector valves, I doubt I would ever use them. I figure all my slides will either be out or all in...I can't think of a reason to just pull one slide out since I can get to everything when they are all in, unless you guys know something I don't please chime in
Allison