Installation: I \"dry-fit\" the inside and outside pieces together. With the inside trim in place, I held it in place with three or four of the mounting screws. I then put masking tape about 1/8th\" outside of the hatch and drilled all of the holes (28). I then removed the hatch and cleaned up all of the aluminum cuttings. I then smeared a generous amount of Silacone in the area inside of the tape and then reset the hatch with all of the fasteners, set just firm. I ran my finger around the joint between the hatch and the aluminum roof, cleaned the excess Silacone off of the hatch, and then removed the tape. Nice, clean installation.