HP, I had the HMS system roof, glass and poppers all worked great, manual release is a mechanical fixing, length of cable which attaches to the lock inside the door and is accessed when the hood is open, the cable needs a hole drilling in the front edge of the door, if the poppers fail or you leave your keys inside the car a sharp tug on the cable will open the door. It also has a locking device with a key so nobody pop the hood and open the door.