You must choose a unique focus for your spell casting. The focus usually takes the shape of a totem or trinket and it is obvious to anyone witnessing you cast that you are using it to cast spells. If the Oracle attempts to cast a spell without his focus in hand, she must make a concentration check or lose the spell. The DC for this check is equal to 20 + the spell’s level. If the focus is lost or destroyed, it can be replaced by spending one week meticulously crafting an identical object to use as a new focus. This focus replaces any material component with a value of 1gp or less.
At 5th level, when using your focus, you gain a +4 bonus to concentration checks when casting
At 10th level, when using your focus, you gain a +2 bonus to caster level checks to overcome spell resistance
At 15th level, when using your focus, you can ignore somatic components of spells.