Spell Focus

Spell Focus item enchantment
Item enchantment of similar name can be found on weapons, bracers (and not rings) and various named items.

+1 versions can be found on
 * Weapons (scepters and such)
 * level 4+
 * level 8+ (foci in two schools, in one item)
 * Bracers
 * level 7+
 * level 15+ (foci in two schools, in one item)

+2 versions (Greater Focus) can only be found on named items
 * Greater Evocation Focus
 * Greater Necromancy Focus
 * Greater Enchantment Focus
 * Greater Illusion Focus

+3 versions (Epic Focus) can only be found on epic named items
 * Epic Conjuration Focus

Spell Focus item enchantments, including Spell Focus Mastery, stack with the feat.