Inside, there's an elastic retainer strap in an "X" shape that buckles in the center. Straps can be removed entirely via clips at each corner. The cylinder lock shown on the top surface (with my ignition key in it) comes with sets of tumblers so you can set it up to accept your ignition key.
The new saddlebags went on today. They're gorgeous and Honda did a nice job with fit 'n finish. The practical test will come over the coming 1000s of miles. Attaching these to the bike is extremely simple.