The La Sportiva Tundra Pants are by far my favorite pants to climb and lounge in and wear around town.
The Tundra pant is made with organic cotton and has an elastic waistband. The waistband is flexible enough where it fits me comfortably and stays put. I'm generally a size medium in most pants and I ordered a size medium in the Tundra pant, which I feel fit perfectly. The pants do not sag or fall when I wear them while running. They're also stretchy enough that I'm not worried about ripping a seam while I'm climbing. I love that the two front pockets are deep enough that my phone, keys, wallet, etc. stay perfectly hidden and don't fall out.
The Tundra pant feels super comfortable to wear. I wore the pants while traveling from San Francisco to Puerto Vallarta in March this year and the pants kept me cozy in our chilly four hour flight. Once we landed in Puerto Vallarta however, I did want to take them off because it was fairly warm and humid there and the pants did not breathe well, if at all. I can see the pants being perfect for a fall trip out to Yosemite or winter trip to Bishop, where you can layer the pants with underclothes and keep nice and toasty.
In terms of durability, I have not had an opportunity to wear the pants outside to climb yet because I received them a little before the COVID-19 shelter in place order, so I cannot speak to how they hold up against rock. I have climbed in the pants at the gym and while using my home wall and I have not noticed any pilling (or ball up), tears, rips, etc. From my experience so far, the pants seem durable enough.
All in all, the La Sportiva Tundra pant is one of my favorite pants to wear at the gym or for everyday wear.