I am so excited to add this to our car!  We have two yorkies and they HATE being put in crates when we have to take them anywhere.  I installed this in the backseat of our SUV and gave it a go.  The setup and install took about 30 minutes from opening the box to installing the booster.  My yorkies were apprehensive at first but then calmed down once they realized they could see out of the window.  We have now been using the booster for about 2 weeks and it is definitely a game changer.  I highly recommend!  For size purposes, my dogs are 9lbs and 14lbs.  It's a little tight with both of them in the booster but they fit when sitting side by side.  When only taking one dog, there is plenty of room for either to lay down and take a nap.  There are two latches in this booster that I can attach to their harnesses to keep them from jumping out, although neither have attempted it.  In all, a great addition for our fur family!