More Space for a Better Night's Sleep The Circuit's semi-tapered rectangular shape provides more room than a traditional mummy sleeping bag, allowing you to move, change position and sleep more naturally throughout the night without feeling restricted.
We find this suitable for
Sea to Summit Circuit Down Sleeping Bag -1C/30F Long Overview
The Sea to Summit Circuit Down Sleeping Bag is designed for adventurers who want lightweight warmth, excellent packability and a more comfortable sleeping shape. Its semi-tapered rectangular design gives you extra room around the hips, knees and feet, making it ideal for campers who dislike narrow mummy bags or prefer to move more freely during the night.
Filled with 650+ fill power Ultra-Dry Duck Down, the Circuit offers reliable insulation while keeping weight and pack size low. The Long version weighs 910g and compresses down to 6 litres, making it a practical choice for camping, backpacking, trekking and travel adventures where space matters. Designed for users up to 198cm tall, it provides additional length without sacrificing comfort or versatility.
Best For
- Backpacking
- Camping
- Trekking
- Travel adventures
- Bikepacking
- Side sleepers
- Taller users
- Spring and summer camping
- Lightweight overnight trips
Materials
Recycled Polyester Shell & Lining
The Circuit uses lightweight 20D recycled polyester fabrics throughout the shell and lining to balance durability, breathability and packability.
The soft-touch brushed lining feels comfortable against the skin and helps improve overall sleeping comfort, especially on longer camping trips and multi-day adventures.
650+ Fill Power Ultra-Dry Duck Down
The Circuit is insulated with 650+ fill power Grey Duck Down with an 80/20 down-to-feather ratio, treated with Ultra-Dry technology to help improve moisture resistance.
This insulation provides an excellent balance of warmth, compressibility and low weight, helping the bag pack down small without compromising comfort in cooler conditions.
Responsible Down Standard (RDS)
The Circuit uses RDS-certified duck down, meaning the insulation comes from sources that meet recognised animal welfare and traceability standards.
Recycled Storage & Compression Sacks
The included compression sack and storage cell are both made from 100% recycled nylon, helping reduce environmental impact while keeping the bag easy to store and transport.
Features & Technologies
Spacious Semi-Rectangular Shape
The Circuit's semi-tapered rectangular design provides more room than a traditional mummy sleeping bag.
This extra space allows you to sleep more naturally, change position more easily and stay comfortable without losing too much thermal efficiency.
Quilt Conversion Design
A full wrap-around zip allows the Circuit to open completely flat and function as a quilt when temperatures rise.
This makes the bag more adaptable for warmer nights, travel use and camping trips where conditions can change quickly.
Precise Ventilation Control
The wrap-around zip system allows airflow to be adjusted from top to bottom, including fully opening the footbox for extra ventilation.
This helps you fine-tune your sleeping temperature without needing to fully unzip the entire bag.
Hybrid Box-Baffle Construction
The Circuit uses hybrid box-baffle construction to help prevent down migration throughout the bag.
This keeps insulation more evenly distributed, helping reduce cold spots and maintain consistent warmth through the night.
Draft Collar & Draft Tubes
A shaped draft collar and continuous down-filled draft tubes help minimise heat loss around key areas of the sleeping bag.
This improves warmth retention when the temperature drops and helps the bag perform more efficiently in cooler conditions.
YKK Anti-Snag Zip System
The YKK #5 coil zipper features an anti-snag plough to help prevent fabric catching during use.
This makes opening, closing and ventilating the bag smoother and easier, especially when adjusting it during the night.
Lightweight Packability
At 910g and compressing down to 6L, the Circuit -1°C Long remains highly packable for camping, backpacking and travel despite its additional length.
The supplied compression sack helps reduce bulk in your pack, while the storage cell helps preserve loft when the bag is not in use.
Features Summary
- Long length sleeping bag
- ISO-tested temperature performance
- Semi-tapered rectangular shape
- 650+ fill power Ultra-Dry Duck Down insulation
- RDS-certified duck down
- Full quilt-opening design
- Wrap-around ventilation zip
- Footbox ventilation options
- Hybrid box-baffle construction
- Shaped draft collar
- Continuous down-filled draft tubes
- Lightweight 20D recycled polyester shell
- Soft-touch recycled polyester lining
- YKK #5 anti-snag zipper
- Compression sack included
- Storage sack included
- Recycled materials throughout
- Non-PFAS construction
Explore More Sleeping Bags
If you're building a complete camping sleep system, it may also be worth exploring our wider range of sleeping bags, sleeping mats, tents and camping accessories.
You can also visit our Sleeping Bags Knowledge Centre for expert advice and top Trekitt gear recommendations.
Trekitt Review The Circuit -1°C Long offers the same comfort-focused design and impressive packability as the shorter versions, while providing extra length for taller users. It is an excellent choice for campers and backpackers who struggle to find sleeping bags with enough room to fully stretch out.
Best for Milder UK Conditions? Yes. The -1°C rating makes this version ideal for spring, summer and milder autumn camping. Pair it with the right sleeping mat and it becomes a reliable, comfortable option for UK overnight adventures.
How Well Does It Pack Down? Very well. Even with its extra length, the Long version compresses down to just 6L. The included compression sack helps minimise pack space, making it suitable for backpacking, bikepacking and travel adventures.
FAQ
Is the Sea to Summit Circuit -1°C suitable for UK camping?
Yes. It is a great option for spring, summer and mild autumn camping in the UK, especially when paired with a suitable insulated sleeping mat.
How warm is a -1°C sleeping bag?
A -1°C sleeping bag is best suited to mild three-season use. It offers more warmth than a summer-only bag, but it is not designed for very cold winter camping.
Is the Long length right for me?
The Long version is 222cm long and is designed for users up to 198cm tall. It provides extra space for taller campers while maintaining the same warmth and features as the shorter versions.
How small does this sleeping bag pack down?
The Long version compresses down to approximately 6 litres, making it easy to pack for backpacking, trekking, bikepacking and travel.
Is this a good sleeping bag for travelling?
Yes. Its low weight, small pack size and adaptable quilt-opening design make it a practical option for travel, hostels, camping trips and lightweight adventures.
What does the wrap-around zip do?
The wrap-around zip allows you to ventilate the bag from top to bottom, open the footbox for airflow or lay the sleeping bag flat like a quilt in warmer conditions.
Does it use recycled materials?
Yes. The shell and lining are made from 100% recycled polyester, while the compression sack and storage cell are made from 100% recycled nylon.