1) Snap frame,easy to change the pictures.
2) Lock,safety and utility.
3) Top grade and mode.

Sizes as follows :

External Size (mm)	Graphic Size (mm)	Visual Size(mm)
500 x 350	440 x 290	420 x 270
600 x 450	540 x 390	520 x 370
800 x 600	740 x 540	720 x 520
950 x 650	890 x 590	870 x 570
1100 x 700	1040 x 640	1020 x 620
1250 x 800	1190 x 740	1170 x 720