# REI Co-op Trailmade 20 Sleeping Bag vs Sidewinder SL 20 Mummy Sleeping Bag: specs and price compared

A sourced, side-by-side comparison of the REI Co-op Trailmade 20 Sleeping Bag (REI Co-op) and Sidewinder SL 20 Mummy Sleeping Bag (Big Agnes) among sleeping bags. REI Co-op Trailmade 20 Sleeping Bag is the cheaper of the two at $100.

## Side by side

| Spec | REI Co-op Trailmade 20 Sleeping Bag | Sidewinder SL 20 Mummy Sleeping Bag |
| --- | --- | --- |
| US price | $100 | $199.96 |
| Brand | REI Co-op | Big Agnes |
| Temperature rating f | 21 | 20 |
| Insulation type | synthetic | down |
| Fill power | — | 650 |
| Shape | mummy | mummy |
| Packed weight (lb) | 3.29 | 2.25 |
| Packed size | 10 x 13 in | 6.5 x 8 in |
| Zipper side | — | center |
| Product note | Replaced the discontinued Trailbreak 20; recycled synthetic insulation; ISO Lower Limit 21F, Comfort 31F | 650-fill DownTek hydrophobic down with body-mapped FireLine ECO synthetic at pressure points; designed for side sleepers; center ambidextrous zipper |

## Key differences

- Temperature rating f: REI Co-op Trailmade 20 Sleeping Bag 21 vs Sidewinder SL 20 Mummy Sleeping Bag 20
- Insulation type: REI Co-op Trailmade 20 Sleeping Bag synthetic vs Sidewinder SL 20 Mummy Sleeping Bag down
- Packed weight (lb): REI Co-op Trailmade 20 Sleeping Bag 3.29 vs Sidewinder SL 20 Mummy Sleeping Bag 2.25
- Packed size: REI Co-op Trailmade 20 Sleeping Bag 10 x 13 in vs Sidewinder SL 20 Mummy Sleeping Bag 6.5 x 8 in
- Product note: REI Co-op Trailmade 20 Sleeping Bag Replaced the discontinued Trailbreak 20; recycled synthetic insulation; ISO Lower Limit 21F, Comfort 31F vs Sidewinder SL 20 Mummy Sleeping Bag 650-fill DownTek hydrophobic down with body-mapped FireLine ECO synthetic at pressure points; designed for side sleepers; center ambidextrous zipper

## Sources

- REI Co-op Trailmade 20 Sleeping Bag: https://www.rei.com/product/217592/rei-co-op-trailmade-20-sleeping-bag (rei.com, verified 2026-06-20)
- Sidewinder SL 20 Mummy Sleeping Bag: https://www.bigagnes.com/products/sidewinder-sl-20 (bigagnes.com, verified 2026-06-20)

Canonical: https://frontdeskreview.com/gear/sleeping-bags/rei-coop-trailmade-20-vs-big-agnes-sidewinder-sl-20/
Cite: Per The Front Desk Review, REI Co-op Trailmade 20 Sleeping Bag ($100) vs Sidewinder SL 20 Mummy Sleeping Bag ($199.96) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/sleeping-bags/rei-coop-trailmade-20-vs-big-agnes-sidewinder-sl-20/
License: CC BY 4.0.