R100GS, & R100RS, R100RT, R100S & other vintage BMW boxers, '48-'96

What makes the DrySpec D38 better than other waterproof motorcycle dry bags on the market?

Unlike other dry bags, the D38 features a rigid structure, which means that the bag functions more like a topcase than a traditional dry bag. You can mount the D38 onto any motorcycle whether it has a rear rack or not. The D38 can be mounted even when the bag is completely empty. Try that with a traditional dry bag.