Unicorn XLSB — Mushroom Substrate Fruiting Bag (Extra Large) *high gas exchange*

The Unicorn XLS-B is the biggest high-gas-exchange mushroom substrate fruiting bag in the range — and when you need serious volume with maximum fresh air exchange, nothing else comes close. Same extra-large dimensions as the XLS-A but with a 5 micron B filter designed for species that thrive with strong gas exchange. Made in the USA since 1990 by Unicorn Bags LLC, the industry's most trusted name in mushroom cultivation bags.

Specifications

• Filter: 5 micron B filter (2" × 3") — high gas exchange, promotes fresh air exchange for species sensitive to CO₂ build-up
• Capacity: Up to 10 lbs (~4.5kg) of substrate
• Size: 24" × 10" × 5"
• Material: 3.0 mil polypropylene — autoclave and pressure cooker safe at 121°C / 15 PSI
• Side-gusseted, reinforced bottom seal — essential at this size

Why Growers Choose the XLS-B

• Extra-large volume with a 5 micron B filter — the combination for high-output grows where strong gas exchange is critical
• The go-to bag for commercial operations growing species that demand high fresh air exchange
• Handles full autoclave cycles at this volume without seal failure or warping
• Trusted by hobbyists + commercial growers worldwide

Prefer controlled gas exchange at this size? The XLS-A uses a 0.5 micron A filter for balanced moisture retention across the widest range of species. Need smaller bags? We also stock the compact 4A and 10A, plus the bestselling 14A for standard fruiting block production.

Need grain spawn bags instead? See our spawn bag range.

The XLS-B is the bag growers move to when they need extra-large scale with high gas exchange. In stock & dispatched quickly from our UK warehouse.