Used Power Pet Door (Wi-Fi) with power supply and collars. I have had this for a couple of years and with a new dog decided to replace it with a manual one as my concern about coyotes getting in the yard has gotten better. The pet opening is 8" x 10", and this unit will fit 75" to 80 1/4" door openings. Comes with 5 collars and some batteries, collar failure has been a problem, but I know 4 of the 5 were working when I removed them this week (the other was a spare). The unit itself has worked well during the time I have owned it.