All machines are excellent internally, even the fair condition machines which show heavier cosmetic signs of wear are an affordable and very safe buy as long as you're not fussy on cosmetics.
Grade A - Excellent Condition - May have the odd tiny scratch / blemish but not visible after 30cm. (Imagine someone has bought this machine and used it for less than a month, there may be the odd tiny scratch / minor blemish on casing.)
Grade B - Good Condition - May have some light scratching / light scuffs visible after 30cm. (Imagine someone has bought this machine and used it for a couple of months, there may be the odd scratching / blemish on the casing)
Fair Condition - May have some heavier scratching / scuffing on the casing. (Imagine a student has bought this machine and used it for a year or so, some more noticeable scratching / blemish on the casing)
All machines, regardless of grading, are excellent internally and come with solid battery life. The Macs pass our thorough internal testing routines and as an extra step - Apple Diagnostics too.