Leki ELS Expander, 18 mm Review Posted by JokePriestess April 9, 2018 in Trekking Poles 18 mm fits upper sections on all Leki poles except the Ultralight series. Excellent item for spare parts kit on long hikes. Easy installation. One pair per package. Replacement 18 mm ELS Expanders for Leki trekking poles. Camping & Hiking Leki Outdoor Recreation Sports & Outdoors