40/40

A 40/40 weapon set is one such that you have two modifiers for each 20% chance of Half Casting time, and 20% chance of half skill recharge.

This does not provide a "40% chance of each". In fact, with halves casting time, you can get up to a 32% chance to halve casting time, and a 4% chance to quarter casting time. With Halves skill recharge, you can get up to a 36% chance to halve skill recharge.

A 40/40 set would be a Wand with a Wand Wrapping of Memory and an "Aptitude not Attitude" inscription and a focus with a Focus Core of Aptitude and a "Forget me not" inscription.