classic crts are 3:4:5 makes a 29 inch 68/72 cm tv : 43,2cm x 57,6cm x 72 cm . add 1 inch for each of the tv mounting brackets . arcade mounting frames will add a few more centimeters , but that differs a lot . it can be 3 cm or 10 cm on each side. 25,28 and 29 inch tubes usually come with a depth of 40-45 cm . only a few are shorter than 40 cm and mostly flat tubes are longer that curved ones .