Sack Ups Protector 18 Knife Holder AC. This knife holder from Sack Ups is silicone treated to prevent rust and to wick moisture away from your knives. The Sack Ups Eighteen Knife Silicone Sack Protector will help keep your knives in pristine condition and looking new. Specifications for Sack Ups Protector 18 Knife Holder: Manufacturer: Sack Ups Closed Length: 5 in Package Contents: Sack Ups 18 Knife Silicone Sack Protector Sack Ups AC807: Protector 18 Knife Holder