Sack Ups Knife Protector Knife Holder Pack of Six AC. This knife holder by Sack Ups is silicone treated to prevent rust and to wick moisture away from your knives. The Sack Ups Two Knife Silicone Sack Protector will help keep your knives in pristine condition just like the day you brought it. Package Contents: Sack Ups 2 Knife Silicone Sack Protector Sack Ups AC803: Knife Protector Knife Holder Pack of Six