Get two sets (just $8.99 ea @ my hydro shop) and put them about as wide as a door frame. I found that just one zipper made the gap too small if the panda is tightly stretched like mine is in my grow tent. Using two zippers together to unzip a door 3' wide is how I like to do it. Give yourself enough room to walk in and out carrying your widest plant. You can get two small magnets, duct tape one to the bottom of the door flap and tape one to the top part of the door, so you can roll the door up and it will stay out of the way after unzipping.