Box leather is their smooth leather, most of their vintage bags come in box. It is very prone to show marks and scratches, but with the use they blends and it is quite easy to restore.
I’ve sent all my Kellys to get leather treatment in October and they are slowly coming back from Paris. My oldest is from 1969. The good thing about H is that they will always service their bags, no matter how old or if bought preloved. They won’t service only if someone outside H has worked on it (f.i. replacement of handle or other parts).
Box and Barenia are quite rare these days because H has some difficulties in finding leather that stand up to their quality standards, so they prefer to offer less items with these leathers rather than releasing items that they consider of inferior quality.
After I got the nautical NF, I’ve been wanting the matching wallet so badly 
one week long I was trying to convince myself that I didn’t need it, because I already have the Clemence and the daily cardholder in DA with rose ballerine lining, but it didn’t help - I continued checking the website every day, whether the nautical Victorine was still available 
sorry for spamming you with pics!