Can I zip two Sea to Summit sleeping bags together?
Zipping two compatible sleeping bags together forms a warm, cozy, comfortable sleep environment for two people. This is a far more flexible option than a double sleeping bag (which explains why there are so few double sleeping bags on the market).
Here is an example of what zipper coupling looks like using our previous year's sleeping bags, the 2023 Ascent and 2023 Women's Altitude.
BUT not all sleeping bags can be zipped together. Below you will find a table which details which Sea to Summit bags can be coupled – there are notes at the bottom which provide further clarification about which side zipper is referred to in the table (and give some caution about zipping non-Sea to Summit sleeping bags to Sea to Summit models).
Current Sleeping Bags
| Model | Year | Zip Side/Type | Zip Compatibility |
| Alpine | 2024 | Left #5 | None |
| Spark 45°F | 2024 | Left #5 | None |
| Spark 30°F | 2024 | Left #5 | None |
| Spark 15°F | 2024 | Left #5 |
Women's Spark 15°F Any STS bag w/ a Right #5 zip |
| Spark 0°F | 2024 | Left #5 |
Women's Spark 15°F Any STS bag w/ a Right #5 zip |
| Women’s Spark 45°F | 2024 | Right #5 | None |
| Women’s Spark 30°F | 2024 | Right #5 | None |
| Women’s Spark 15°F | 2024 | Right #5 | Any STS bag w/ a Left #5 zip |
| Spark Pro | 2024 | Left #5 | Any STS bag w/ a Right #5 zip |
| Ascent | 2024 | Left #5 | Any STS bag with a Right #5 zip |
| Women's Ascent | 2024 | Right #5 | Any STS bag with a Left #5 zip |
| Trek | 2024 | Left #5 | Any STS bag with a Right #5 zip |
| Women's Trek | 2024 | Right #5 | Any STS bag with a Left #5 zip |
| Basecamp | 2024 | Left and Right #5 |
Basecamp Any STS bag with a Right #5 zip |
| Traveller | 2024 | Left #5 | 2024 Traveller w/ the same zip length |
| Traverse TV | 2019-2024 | Left #5 | Any STS bag w/ a Right #5 zip |
| Venture | 2019 - 2024 | Right #5 | Any STS bag with a Left #5 zip |
| Trailhead | 2019-2024 | Left #5 | None |
| Quest | 2019 - 2024 | Right #5 | None |
Past Sleeping Bags
| Model | Year | Zip Side/Type | Zip Compatibility |
| Alpine | 2010-2023 | Left #5 | None |
| Spark I | 2015 – 2023 | Left #3 | None |
| Spark II | 2017 - 2023 | Left #3 | None |
| Spark III | 2017 – 2018 | Left #3 | None |
| Spark III | 2019 - 2022 | Left #3 | Any STS bag with a Right #5 zip |
| Spark IV | 2019 - 2022 | Left #3 | None |
| Spark IV | 2023 | Left # 5 | Any STS bag with a Right #5 zip |
| Flame I | 2015 – 2023 | Right #3 | None |
| Flame II | 2017 - 2023 | Right #3 | None |
| Flame III | 2017 – 2018 | Right #3 | None |
| Flame III | 2019 - 2022 | Right #3 | None |
| Flame III | 2023 | Right #5 | Any STS bag with a Left #5 zip |
| Flame IV | 2019 - 2022 | Right #3 | None |
| Flame IV | 2023 | Right #5 | Any STS bag with a Left #5 zip |
| Ascent | 2019 – 2023 | Left # 5 | Any STS bag with a Right #5 zip |
| Altitude | 2019-2023 | Right #5 | Any STS bag with a Left #5 zip |
| Trek | 2010-2023 | Left #5 | Any STS bag with a Right #5 zip |
| Women's Trek | 2016-2018 | Right #5 | Any STS bag with a Left #5 zip |
| Traverse XT | 2010-2016 | Left #5 | Any STS bag with a Right #5 zip |
| Micro | 2010-2016 | Left or right #3 | Only 2010-2016 Micro with opposite zipper side |
| Micro | 2017 - 2018 | Left or right #5 | Any STS bag with opposite zipper side #5 zip |
| Traveller | 2016 – 2023 | Left #3 | Another 2016 – 2023 Traveller of the same length |
| Talus | 2012-2018 | Left #5 | Any STS bag with a Right #5 zip |
| Latitude | 2016-2018 | Left #5 | Any STS bag with a Right #5 zip |
| Women's Talus | 2016-2018 | Right #5 | Any STS bag with a Left #5 zip |
| Women's Latitude | 2016-2018 | Right #5 | Any STS bag with a Left #5 zip |
| Amplitude | 2019-2022 | left and right #5 | Another Amplitude/Basecamp or any STS bag with a #5 zip |
Note - in the above table, the zipper referred to is the main side zipper. Some bags also have a footbox zipper; some have a secondary short side zipper. The zipper used to couple two sleeping bag together is always the main side zipper.
The zipper descriptions relate to Sea to Summit sleeping bags. A sleeping bag from another brand may zip together with a Sea to Summit bag provided the zipper is the same size and has the same teeth oriented in the same way facing inwards. In case of doubt when trying to couple two bags, do not force a zipper slider - damage can result to the zipper slider or zipper track.
