Flex PR vs Flex PR Plus: Which Pack Rafting Backpack?
By Six Moon Designs | Published: 2026-10-18
Category: Comparisons
Compare the Flex PR and Flex PR Plus pack rafting backpacks from Six Moon Designs. Learn the key differences in volume, weight, and value to choose the right raft pack for your trips.
Quick Answer
The Flex PR (50L, 58.6 oz) suits day trips and ultralight rafters who prioritize a smaller profile. The Flex PR Plus (75L, 59.6 oz) adds 25L of capacity for multi-day expeditions or bulkier gear, with only a 1 oz weight penalty. Choose the Plus if you need the extra space; pick the PR if you want the lightest, most compact option.
Volume and Weight Trade-Offs
The most obvious difference between the Flex PR and Flex PR Plus is internal volume. The Flex PR holds 50 liters, while the Flex PR Plus expands to 75 liters. That extra 25 liters lets you carry a full pack raft, paddle, PFD, overnight gear, and food without compression struggles. However, the weight difference is surprisingly small: the Flex PR weighs 58.6 oz, and the Flex PR Plus weighs 59.6 oz — just one ounce more for 50% more capacity. Both packs use the same removable suspension system and dry bag construction, so the added volume comes almost entirely from the bag's larger dimensions, not heavier materials.
If you routinely pack for multi-day river trips or need to carry bulky items like a dry suit or extra camera gear, the Flex PR Plus is the practical choice. For shorter day floats or minimalist overnighters where every cubic inch counts, the Flex PR keeps your load tighter and more manageable.
Dry Bag Design and Suspension
Both the Flex PR and Flex PR Plus are built as dry bags with a fully removable suspension system. This means you can detach the shoulder harness and hip belt and use the bag as a standalone waterproof duffel for rafting, canoeing, or camp storage. The suspension is designed for heavy loads — up to 50–60 lbs comfortably — making both packs suitable for portaging or carrying gear over trails. The key difference is that the Flex PR Plus's larger bag can hold more volume before the suspension reaches its load limit, so you can actually use that capacity without overstuffing.
Neither pack includes a frame sheet, so load transfer relies on the hip belt and compression. If you plan to carry very dense loads (e.g., multiple liters of water or heavy camera gear), the larger Flex PR Plus gives you more room to distribute weight, but the suspension feel is identical between the two.
Trade-Offs to Consider
- Capacity vs. Packability: The Flex PR Plus holds 25L more gear, but its larger bag can feel bulky when underfilled. The Flex PR compresses smaller and fits more easily in tight boat storage or under a seat. Choose the PR if you value a compact load; choose the Plus if you need the space.
- Weight vs. Volume: The Flex PR Plus weighs only 1 oz more than the Flex PR yet offers 50% more capacity. That is an excellent volume-to-weight ratio, but the PR remains the lighter option for those counting every gram. The weight penalty for extra capacity is negligible for most users.
- Price vs. Value: The Flex PR is priced at USD 204.40 (catalog comparison USD 280.00), while the Flex PR Plus is USD 211.05 (catalog comparison USD 315.00). The Plus costs about USD 7 more but gives you 25L additional volume and a higher catalog value. The Flex PR Plus offers better dollar-per-liter value if you need the space.
Product Facts at a Glance
- Flex PR Pack Rafting Backpack: 58.6 oz (1660 g) pack weight; 50L dry bag with removable suspension system designed for carrying heavy loads in comfort. The 50L capacity is ideal for day trips or minimalist overnighters where you want the smallest, lightest pack that still offers full dry bag protection and a comfortable carry.
- Flex PR Plus Pack Rafting Backpack: 59.6 oz (1690 g) pack weight; 75L dry bag with removable suspension system designed for carrying heavy loads in comfort. The 75L capacity gives you room for multi-day gear, a larger raft, or extra layers, with only a 1 oz weight increase over the 50L version, making it the better value for volume.
Which Pack Rafting Backpack Fits You?
Best For
- Day trippers and ultralight rafters who want the smallest, lightest dry bag pack
- Travelers who need a pack that doubles as a compact duffel for short trips
- Rafters on a budget who don't need the extra 25L capacity
Not For
- Multi-day expeditions where 50L forces you to leave gear behind or overstuff
- Rafters who carry bulky items like a dry suit, large camera kit, or extra food for a week
