To avoid the hassle of ever not having one when a lifty decides to actually enforce the rule...and it's happened many times. From experience, I know how much it sucks to have either hike back to the car to get it, or wait in line forever and shell out $10 at the rental shop. I keep one in my pocket as often as I can remember.
14 NeverSummer Prospector Splitboard . 14 NeverSummer Proto HD . 13 NeverSummer Cobra . 13 Gnu Space Case EC2PTX. 11 Nitro Team Gullwing
14 Now Drive . 13 Now IPO . 13 Salomon Hologram
14 Flow Hylite . 13 32 Binary