A:AnswerCopy and paste and go here - https://tvna.compal-toshiba.com/us/wp-content/uploads/sites/2/2016/07/Toshiba_43L420U_49L420U_17-0084_WEB_V5_EN_Final_lr.pdf
A:AnswerI used M11 size, I think they were about 2"...I had the same problem, my mount only included short screws, and the casing around the mounting holes on the tv adds a lot of depth.