I bought my Hein Geriecke (sp?) leather jacket about 15 years ago. It came with two spritz-bottles of stuff - one a cleaner/conditioner and the other a water-proofer. I used them once when I first bought the jacket then never again until just this past winter, although they've come with me through three moves since then!
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The jacket was getting a little stiff, and it had quite a few bugs on it, so I thought I'd give it a try again. Together, they've made that jacket soft and supple as new again! I was very impressed. Kinda ironic that I never used 'em all the life of the jacket until now.
Since we ride year-round here in FL, I've ridden probably 20 ~ 30k miles wearing that jacket (among others), and it's hanging in my cubicle at work right now. Rode in this morning wearing it...
So, that's just for what it's worth...
Kirk