Black Diamond's Trekking Pole Carbide Tips allow you to rejuvenate your trekking poles when the tips wear down.
Black Diamond says:
For added bite on hard or slippery surfaces, the Black Diamond Carbide Tech-Tips provide durable and secure performance. Works as replacement tip for our Spring 2012 and later only trekking poles and all model Z-poles. Does not work with First Strike, Trail Back, Syncline poles. Sold in pairs.
Black Diamond's Carbide tips are quite tricky to fit - but at least you're doing this at home - rejuvenate your poles by replacing those worn out tips.