# Disco Men's Endless Promise Down Sleeping Bag 15F vs Sidewinder SL 20 Mummy Sleeping Bag: specs and price compared

A sourced, side-by-side comparison of the Disco Men's Endless Promise Down Sleeping Bag 15F (NEMO Equipment) and Sidewinder SL 20 Mummy Sleeping Bag (Big Agnes) among sleeping bags. Sidewinder SL 20 Mummy Sleeping Bag is the cheaper of the two at $199.96.

## Side by side

| Spec | Disco Men's Endless Promise Down Sleeping Bag 15F | Sidewinder SL 20 Mummy Sleeping Bag |
| --- | --- | --- |
| US price | $299.95 | $199.96 |
| Brand | NEMO Equipment | Big Agnes |
| Released | 2024 | — |
| Temperature rating f | 15 | 20 |
| Insulation type | down | down |
| Fill power | 650 | 650 |
| Shape | spoon | mummy |
| Packed weight (lb) | 2.69 | 2.25 |
| Packed size | 11.5 x 8.5 in | 6.5 x 8 in |
| Zipper side | left | center |
| Product note | Classic Spoon shape (mummy variant with extra shoulder/hip width); 650 FP PFAS-free hydrophobic RDS-certified down; Thermo Gill vents | 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: Disco Men's Endless Promise Down Sleeping Bag 15F 15 vs Sidewinder SL 20 Mummy Sleeping Bag 20
- Shape: Disco Men's Endless Promise Down Sleeping Bag 15F spoon vs Sidewinder SL 20 Mummy Sleeping Bag mummy
- Packed weight (lb): Disco Men's Endless Promise Down Sleeping Bag 15F 2.69 vs Sidewinder SL 20 Mummy Sleeping Bag 2.25
- Packed size: Disco Men's Endless Promise Down Sleeping Bag 15F 11.5 x 8.5 in vs Sidewinder SL 20 Mummy Sleeping Bag 6.5 x 8 in
- Zipper side: Disco Men's Endless Promise Down Sleeping Bag 15F left vs Sidewinder SL 20 Mummy Sleeping Bag center
- Product note: Disco Men's Endless Promise Down Sleeping Bag 15F Classic Spoon shape (mummy variant with extra shoulder/hip width); 650 FP PFAS-free hydrophobic RDS-certified down; Thermo Gill vents 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

- Disco Men's Endless Promise Down Sleeping Bag 15F: https://www.nemoequipment.com/products/disco-mens-endless-promise-down-sleeping-bag (nemoequipment.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/nemo-disco-15-endless-promise-vs-big-agnes-sidewinder-sl-20/
Cite: Per The Front Desk Review, Disco Men's Endless Promise Down Sleeping Bag 15F ($299.95) vs Sidewinder SL 20 Mummy Sleeping Bag ($199.96) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/sleeping-bags/nemo-disco-15-endless-promise-vs-big-agnes-sidewinder-sl-20/
License: CC BY 4.0.