I don't think they have any specifics, that's up to those that are shipping them. I know Shark scrapper did a Youtube video where he uses 3x5 index cards, folds the card and staples the edges dropping the processor in before stapling the top part to seal in the folded card.
For me I've used these 3x5 anti-static bags with zip locks
https://www.ebay.com/itm/353535643027Works good for the buy program since all the processors are pinless. I add some bubble wrap to the bottom of the box, then stack the processors in the bags. I add more bubble wrapping on top and add enough to press them down in place so if you shake the box they don't move, these bags are longer than the processor so I was flipping them around so they stacked nicer.
I may have added the box of processors into a larger box, been a while since I sent them in. I want to say the last batch I added the box in a larger box with Laptop motherboads.