The material below is Open Game Content from a 3PP Source
Banded Mail of Luck
Aura strong enchantment; CL 12th
Slot armor; Price 18,900 gp; Weight 35 lbs.
Ten 100-gp gems adorn this +3 banded mail. Once per week, the armor allows its wearer to require that an attack roll made against him be rerolled. He must take whatever consequences come from the second roll. The wearer's player must decide whether to have the attack roll rerolled before damage is rolled.
Requirements Craft Magic Arms and Armor, bless; Cost 9,650 gp