Altrec.com:

Designed with the same waterproof performance found in HydroLite sacks, Outdoor Research Hydroseal Pack Sacks feature a highly durable Antron nylon fabric that enhances overall durability, making these sacks excellent for rolling across abrasive surfaces like open rock faces while climbing. Hydroseal Pack Sacks even feature external daisy chains for easy clip-in attachments. Granted, you don't want to throw out your durable climbing haul bags and replace them with these lighter sacks, but the extra grams of protection are excellent if you can't hassle with frayed or potentially fragile storage sacks.

Moosejaw.com:

Outdoor Research Hydroseal Pack Sacks (Fall 2008) The Hydroseal Pack Sacks by Outdoor Research. Specifications: #1 Avg. weight: 1.8 oz./51 g Dimensions: 13 x 6 /33 cm x 15 cm Volume: 368 cu. in./6.0 L Specifications: #2 Avg. weight: 2.1 oz./60 g Dimensions: 15 1/4in. x 7in./39 cm x 18 cm Volume: 587 cu. in./9.6 L Specifications: #3 Avg. weight: 2.6 oz./74 g Dimensions: 17 1/2in. x 8in./44 cm x 20 cm Volume: 880 cu. in./14.4 L Specifications: #4 Avg. weight: 3.2 oz./91 g Dimensions: 19 3/4in. x 9in./50 cm x 23 cm Volume: 1256 cu. in./20.6 L Specifications: #5 Avg. weight: 4.0 oz./113 g Dimensions: 21 1/4in. x 11in./54 cm x 28 cm Volume: 2019 cu. in./33.1 L Specifications: #6 Avg. weight: 5.4 oz./153 g Dimensions: 22 3/4in. x 13in./58 cm x 33 cm Volume: 3020 cu. in./49.5 L Features: Hydroseal coated Antron nylon is waterproof and durable Waterproof taped seams Draw cord and Hypalon cord lock keeper closure Reversed tunnel eases cinching Dust flap Webbing bottom handle External daisy chain