"Amazing warmth for the weight. Very light and very warm the K Series Hispar 400 bag has by far the best warmth to weight ratio of all the bags tested. If you want the maximum warmth for the least weight...this is the bag to choose"
— Chris Townsend, TGO Magazine's test of 3 season sleeping bags.
"I used my Hispar 400K on a three week trip to Everest Base Camp via Gokyo Ri and over the Cho La pass. With 18 nights in varied temperatures down to -1c at our tented camp at the base of Kala Patthar I can safely say this is a brilliant bag. Just 875g, mine is long and has a full length zip, it performed exceptionally well and for such low weight. Whilst not a test down to the rated -9c I am a 'cold' sleeper and I know I could have gone further down than -1c in comfort, trust me for me that is a testament to the bags warmth. Thank you PHD."
— Rob Pinate
The reviews below relate to standard Hispar 400, which is 135g heavier
"This has to be the best sleeping bag I've ever used in every respect. It's warm as a very warm thing (good to -9). It's not cheap but then you get what you pay for when it comes to sleeping bags. PHD are a very small company but they beat the socks off the big guys."
— Phil Newby, registered BAIML International Mountain Leader.
"I have a new Hispar 400 which is proving to be very good indeed."
— Tim Rodgers.
"I have one of your Hispar Bags and think they are amazing."
— Richard Bishop.
"In September, I had the opportunity to use my Hispar 400 bag in Iceland. The bag was so warm that I didn't need to close the zipper!"
— Volker Junge.
"Having ordered a Hispar from you last month and testing it wild camping in North Wales to around -2 degrees, I have to admit that the bag is brilliant! I was toasty while my climbing partner shivered! Thank you for the excellent gear and hopefully my down jacket will be falling apart soon so I can justify replacing it with one of yours!"
— Alistair Ross.