I have never had a problem with my BD Contours every jamming up or slipping. I swear by the FlickLock.

I am also going to get a pair of the BD' new Spire Trekking Poles. I've not been able to break my Contours in over 700 miles of use (and I have broken every other trekking pole I have tried) , but the Spires look even sturdier for only one ounce more. I will try them out on the Tahoe Rim Trail and John Muir Trail this summer.
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http://www.trailjournals.com/BearpawAT99/