This offer is available to Prime members only. Offer only applies to the purchase of select products sold by Amazon.com. See offer page for details. Offer does not apply to digital content. Offer good while supplies last. Shipping charges and taxes may apply to discounted and free promotional items. Items must be purchased in a single order and shipped at the same speed to a single address. Offer limited to one per customer and account per participating Sample Box. Offer may not be combined with other offers. The maximum benefit you may receive from this offer is a promotional credit equal to the purchase price of your Sample Box.
Source : https://9to5toys.com/2017/10/11/amazons-mens-grooming-sample-box/