XS Scuba Tail Weight Pouch. 

Features: 

• Designed for adjusting your trim when using double cylinders 
• Attach with lower cylinder band bolt
• Two stainless steel grommets for attachment 
• Sealed opening with double Velcro® closure 
• Holds up to 6 lbs. of #5 or smaller lead shot
• Wide opening allows the use of hard weight up to 5 lbs.