SRD:Ring of Clumsiness

Ring of Clumsiness: This ring operates exactly like a ring of feather falling. However, it also makes the wearer clumsy. She takes a –4 penalty to Dexterity and has a 20% chance of spell failure when trying to cast any arcane spell that has a somatic component. (This chance of spell failure stacks with other arcane spell failure chances.)

Strong transmutation; CL 15th; Forge Ring, feather fall, bestow curse; Price 500 gp.