It is planned to mount the wall bracket/TV on a wall which is stable enough but not very thick (approx. 4.5 cm, as a sliding door is built in). How deep into the wall do the screws supplied go, or how long are the screws? I am mainly interested in knowing whether special screws are necessary. I don't want the fitter to have only the screws supplied and then have to come twice. :) With double costs. $