BTW, I've found an easy path to assembling a little kit for dayhikes is to start with a commercial 1st aid kit in a pouch--there are several decent brands with many sizes offered--and add a small flashlight/headlamp, lighter, small knife, whistle, water treatment tablets, compass. All these extras fit easily.

Compact, easy to pack and easy to find. In sketchy weather I toss a bivy sack and poncho in the rucksack as well, providing emergency shelter.

Cheers,