Double X Tackle Tough Bubble - Manufactured of tough Butyrate Plastic! Water fillable for greater casting distance! Tough Butyrate plastic. Tough Bubble Made in Berthoud, Colorado, U.S.A.! This bubble will withstand a whole lot more than other wimpy imitations! It's the perfect fit for fishing a fly or bait, live or artificial. Tough Butyrate plastic Water fillable for great casting distance Made in Berthoud, Colorado U.S.A.