I have the large slant version of these:
http://riverroadgear.com/spectrum-series/spectrum-textile-saddlebags.htmlThe zipper "locks", with a dinky padlock. (padlock purchases separately)
Will it stop someone determined to get in? No.
Like any lock, it only deters, it does not prevent.
The zippers that hold the bags to the yoke does NOT lock. But those are covered and not obvious.