0603, 0805, 1210, 5050, refers to the LED lights take use size – LED light-emitting component (imperial/metric), below is the specification in detail:
0603: the conversion to the metric system is 0603, it indicates that the length of the LED element is 1.0 mm, width is 0.5 mm. Industry referred to as “1005, British system name is 0603.
0805: the conversion to the metric system is 2125, it indicates that the LED components, length is 2.0 mm, width is 1.25 mm. The industry referred to as “2125, British system name is 0805.
1210: the conversion to the metric system is 3528, it indicates that the length of the LED element is 3.5 mm, width is 2.8 mm. Industry referred to as “3528, British system name is 1210.
5050: this is a metric called, it indicates that the LED components, length is 5.0 mm, width is 5.0 mm. Industry referred to as “5050.