Update:In addition to the items below, the unit did not come with an IR sensor. The “obstruction technology“ does work, But you must set the number 4 pin switch properly until you have successfully tested that it will stop against your weight. In addition, you will have to test it over a few days, because if you set the Resistance Dial too loosely, it will not fully close and will back up. Once you get to sufficient resistance though, it sufficiently closes and opens. The lack of an IR sensor is an issue, and HappyBuy Sent a whole new unit but it still did not have one.Nevertheless, I have now used this device for several weeks, and if you are mechanically handy, it ends up being a very effective and usable unit. I purchased a separate garage door “Smart“ Internet connected opener which really makes things handy. I bought the following unit on Amazon and it was relatively cheap and is compatible- HBN Smart Garage Door Opener - Connected WiFi Garage Door Control, Compatible with Alexa & Google Home Assistant, No Hub Needed. See my separate review of that product, which has some issues but for the price has worked. Overall I’ve changed my recommendation of this from three stars to four stars if you can handle the issues described, given that the sells for $180-$200 and has a 3100 pound stated capacity, which is far more than almost all of the other sold.Original review:This unit does not come with an electrical cord or any way to plug it in. Seriously? If intended to be hardwired, and not plugged in they should be clearly stated as either way you’re gonna have to your own hardwire, or a 15amp plug/wire to connect to this to make it work. The instructions are atrocious, and really poorly written. This requires installation of two separate limiter magnets, but you have to be mounted above each other, which might not be possible for all gates. NOTE: advertised parts included says “1 X 20ft. of Chain” -The unit come with two chains though, that appear to be 2-10’ foot
Javier 
Miguel A Ruiz 
