Alpine Trekkers are obsolete. Please save yourself the hassle and money and buy a real AT binding. Sure they eventually do the job and you get to use your own burly bindings, however, the drawbacks far outweigh the benefits. First off, the trekkers take up so much time during a day of touring. Making laps is hard b/c you must take your skis off and the trekkers out of your bindings to ski down then pull them out of your pack and fiddle with them till they sit in your bindings right. Sounds easy, but the trekkers always put up a good fight. Second, they break. The heel piece on mine snapped the first day i skied them. Finally, if you ski Rossi binders or another binding with a really tall heel piece, dont even bother. the heel of your boot will come down on the heel piece of the binding and not let go all the way down to the 0 degreee position (major pain on long flats). The Day Wrekkers are no longer a necessity to get into the backcountry and a Fritschi, Duke, or MFD is a much better option.