make it possible to wear the ForeRunner outside the sleeve of you jacket - the extender even make it fit outside several layer of clothing and above the wrist . I use the ForeRunner to navigate home on ski through whiteout condition in the mountain - have it on my arm so that I could see it all the time without have to take off my glove or put aside my skiing pole . in -10 degree c -lrb- 14 degree f -rrb- that be kind of nice . look for a really useful GPS unit ? Make sure you can use it in really cold condition without freezing you finger to icicle ... for normal use , I find this strap work much better than the regular plastic wrist strap which come with the unit , and be very comfortable - especially on sweaty skin . note : I would not recommend the ForeRunner as you only or primary wilderness gp -lrb- one reason be that the battery be not replaceable -rrb- . and do not leave home without a map and a compass - and the knowledge to use they ...