Pathfinder treasure generator website, those of you that use it, could you explain this for me please?

[cmastah]

Those of you that use this treasure generator, (http://pathfinder.zonegamma.com/index.php), could someone please explain to me what these mean:

Arcane Scroll, Astral projection {9th/17th}
Potion of Shrink item {3rd/5th}

What does 9th/17th mean? Or the 3rd/5th thing mean?

[Pirate Rob]

Spell level/Caster level

[cmastah]

Thanks, those numbers were driving me crazy.