Osprey Ultralight Protective Backpack Liner, Medium - Rain Protection

In this review of the Osprey Ultralight Protective Backpack Liner, Medium, the bottom line is straightforward: this is a lightweight, purpose-built liner for hikers and pack travelers who need reliable wet-weather protection for a 50-70 liter pack. The reviewer found the liner excels at keeping gear dry while fitting neatly inside compatible packs, and its featherlight weight means it adds almost no burden on long approaches. If the primary concern is waterproofing a single pack without extra bulk, this liner is an easy choice.

Key Features

• Shaped fit: The liner is contoured to sit inside common backpack shapes, which helps it hug gear and avoid excessive shifting while hiking.
• Water protection: Designed to block rain and wet conditions, the liner protects clothing and electronics from moisture.
• Lightweight: At roughly 0.26lb, it adds virtually no carrying weight, making it suitable for long-distance days and overnight trips.
• Pack capacity compatibility: Sized for 50-70 liter packs, it works with medium-sized internal pack volumes without unnecessary excess material.
• Compact storage: The simple construction packs down small when not in use, freeing space for other essentials in the bag.

Who It's For

The liner is best for backpackers, overnight hikers, and commuters who carry a medium 50-70 liter pack and want to safeguard gear from rain without adding weight. It is especially useful for those who already own Osprey-style packs or similarly tapered backpacks where a shaped liner improves fit and reduces internal movement.

Those who should look elsewhere include travelers needing an external rain cover for the whole pack exterior, or users with very large or very small packs outside the stated 50-70 liter range. If you need internal organization pockets or heavy-duty abrasion resistance, a more substantial dry sack or pack cover may be preferable.

Pros & Cons

Pros

• Reliable waterproofing that customers consistently praise for keeping contents dry.
• Very light at about 0.26lb, so it minimally affects carry weight on long treks.
• Shaped to fit medium backpacks, reducing slop and improving internal pack stability.
• Compresses small for easy stowage when not in use.

Cons

• The medium sizing for 50-70L packs may be too small for some users or pack models, so size selection matters.
• As a simple liner, it lacks internal pockets or heavy reinforcements for rough handling.

Specifications

Brand	Osprey
Model	Ultralight Protective Backpack Liner, Medium
Item Dimensions	24H x 14.6W x 12.2D in
Item Weight	0.26lb
Pack Compatibility	Designed for 50-70 liter packs
Color	Black

Our Verdict

The Osprey Ultralight Protective Backpack Liner, Medium, is a sensible, value-minded choice for anyone who needs dependable internal waterproofing for a 50-70L pack. Its low weight and shaped fit make it particularly good for multi-day hikers who prioritize keeping gear dry without extra bulk, though buyers should confirm size compatibility with their pack model.

Frequently Asked Questions

Will this liner fit a 60 liter pack?
Yes; the medium size is specified for 50-70 liter packs and fits most 60L backpacks that have an internal shape compatible with Osprey-style liners.

Is the liner truly waterproof?
Customers report the liner keeps contents dry in wet and rainy conditions, making it effective as an internal waterproof barrier.

How much weight does it add?
The liner weighs about 0.26lb, so it adds almost no noticeable weight to a loaded pack.