It depends on which Ultra Minnow mold you get. For the mold with 1/4oz, 3/8oz and 1/2oz. you will need 0.035 for the 1/4 and 0.040 or 0.041 for the other 2 sizes. For the mold with 5/8oz, 3/4oz, and 1oz you will need 0.040 or 0.041 for all of the cavities.