shoulder pads

..just looking at types of shoulder pads; what are the important 'variables' to consider when developing a shoulder pad.
http://www.dritz.com/brands/showcase/details.php?ITEM_NUM=53090
this site gives some information on shoulder pads.
We have shoulder pads called Covered Set-In Shoulder Pads and these seem to be one of the main types of shoulder-pads. What does 'covered' mean here? What does set-in mean? In designing a shoulder pad, it is important how to 'set-in' the shoulder pad...how should the pad be set-in to the garment and ..then the shape of the shoulder pad is important..the pad should give the right 'effect' that the wearer wants....or if the wearer doesn't want a specific effect, then the fit of the shoulder pad should be suitable...maybe as said the person just wants to 'raise' the shoulder line and simply doesn't want slanting shoulders..this should be considered....

What does the wearer want the shoulder pad for?
Then..there is another type of shoulder pad called 3/4" Covered Raglan. I am not familiar with the world of shoulder pads..but maybe this pad is to be worn in a raglan sleeve... There is the 3/4 " covered raglan above..and then there is a 1/4" Covered Oval Raglan by Dritz.

http://www.dritz.com/brands/showcase/index.php?BRAND_ID=5&SUBCAT_ID=35