Fresnel Magnifying Lense drastically enlarges the size of a small touch screen. Tired of squinting to read tiny text? This is the solution! Magnify any small screen up to 7 x 4.7 inches. Diagonally this equates to 8.5 inches. Flat Surface is definitely recommended for mounting. Preferably a metal surface that is attracted to magnets. So, most stainless steel and all aluminum won't attract the magnets. Even if there is not a metal surface available to attract the magnets, the mounting bracket can still be attached with Double Sided 3M Tape or M4 Flat Head Bolts. There are 4 counter sunk bolt holes underneath where the magnets go. These bolt holes also make it easy to remove the magnets. Simply push a small rod such as an Alan wrench into the bolt holes to push the magnets out of their recessed bed. Double Sided 3M Tape will be included in your purchase of this item.