Question about ritek dvd-r

[toviolent]

I have been reading a lot of post about different grades of these dvd-r disk how will I know which grade of disk I would get is there something on the wrapper like a number or something and a second question is in the U.S is there any stores that are known to sell these like walmart kmart staples any other. The reason for asking is so I would be able to know what grade im getting thanks in advance