First let us get some terminology out of the way. So we are on the same page.

Micro: About the size of an old fashion pocket watch or smaller. These are usually job specific. Fire, water, fishing, ETC. The design is for these kits to be scattered around your person or gear to be combined to form a survival kit. The ultra small [micro] size makes for compact storage.

Mini or PSK: The size is to fit conveniently in a pocket. This should be a daily carry item. The standard is usually based on the Altoid tin. This is the true stand-alone survival kit. These kits try to meet the minimum needs in most situations. This can be made up of several micro kits.

Maxi: The next step up in size and level of convenience. Usually from the size of a large paperback book to a hard bound one. This is where shelter material is starting to be added. You step up to this when you are planing to leave the beaten path.

Pack: This is the size of a butt or daypack. This is where you start adding food for several days. Such as a 72 hour kit. Usually combined with full camping gear. Carry this for short side trips or even if just going over there. If you go out of sight of the main camp you may need it.

Large: This is your camping gear and supplies for and extended trip out and beyond.

What the Idea of a PSK is to have the minimum gear when the only thing you have left is your pockets. Too often people keep adding gear until the kit is to big to fit in a pocket. Then it is not carryed. More gear is desireable and a PSK is really a last resort back up.