Samaya NANO BIVY - Tutorial

The Samaya NANO BIVY has been designed for ultralight and minimalist practices, but also for safety, at the bottom of the pack, during an alpine-style race. Made from our own tent materials, it offers the perfect combination of lightness, durability and performance.

This waterproof and breathable bivy sack is the ideal partner for roaming. Designed to protect your sleeping bag from the elements, it allows you to leave safely, even without a tent.

The dimensions of Samaya NANO BIVY have been carefully thought out to accommodate your sleeping bag and mummy mattress, creating a solid, protective unit for your nights in the mountains.

[robm]

If that is as I presume DCF, then in my opinion and experience, it is being wrapped too tightly.
Secondly, if the temperature warms up during use, it is going to be difficult to vent adequately.
As I age, I find environmental control to be more and more important, e.g., with tents, but also bivy bags. But I am pretty impressed with your products.