This is a keyguard for the classic Dell AT101W keyboard.  This is a full-size typewriter-style keyboard with full-height keys. Though not made anymore, you can still buy used and refurbished ones. 

This item does not come with a keyboard. This is to order the keyguard only.

This keyguard is secured with provided Dual Lock fasteners.

Material - The keys are just under 1/8" high, so if you pick an 1/8" material, the top of the keys will be just below the surface of the keyboard. Most people prefer a material of 3/16" or greater, to give a little depth to the holes, requiring a more deliberate touch.  1/4" materials make for even deeper holes. A popular choice is polycarbonate, which has a lifetime guarantee against breakage and nice, bevelled edges which make the keyguard softer to the touch.