When I switched over to a 28 liter pack for three season camping neither of my previous sleeping bags, a North Face Blue Kazoo or a Sierra Designs 600 fill bag would fit in the pack. Well they fit, but they took up more than half the pack. Those old sleeping bags weren't going to fit in with my smaller and lighter philosophy anyway.
The Mountain Hardware Lamina 45 turned out to be the solution I was looking for. I've been using mine for two full years and am very pleased with all aspects of the bag. Let's go down the checklist.
The Lamina 45 is rated for temperatures down to 45 degrees Fahrenheit or 7 degrees Celsius making it a true three season bag (at least here in the south eastern US). However, I've used my Lamina 45 in temperatures all the way down to just above freezing. In those situations when it got near freezing I was insulated in my Oware bivy and wearing my extra layers of clothes. Given that I improvised it is possible to push the limits of Lamina 45, but I would give the bag a personal low limit of around 34 degrees Fahrenheit or 1.1 degrees Celsius.
Weighing (on my scale) 1.6 pounds or 725 grams the Mountain Hardware Lamina 45 is well within the ultralight weight range. And it packs down real small. The Lamina 45 comes with a stuff sack that compresses the bag to the size of a football with the ends cut off. The Lamina 45 packs small enough to fit in my hand and is smaller in size than my Them-a-rest Prolite Plus.
The Lamina 45 is a synthetic bag. While there is an argument against synthetics, that they aren't as light as or pack down as small as a down bag, the weight and size of the Lamina 45 is comparable with the lightest down bags. A plus to synthetics is they will keep you insulated when wet and will also dry fast. I've never had any problems with condensation forming on the bag. I have gotten the bag a little wet at night down on the foot end, but it didn't compromise the Lamina 45's insulating ability. The next morning I was able to hang the Lamina 45 on a line and with a slight breeze it dried in less than thirty minutes.
The Lamina 45 has a hood that tightens by a single draw cord, it forms a good seal keeping out wind and cold. In the shoulder area just below the hood on the opposite side from the zipper is a small zip pocket and a small velcro pocket. I don't ever use the pockets but they are functional.
The Lamina 45 has a double zip so it can be vented at the foot end.
I made one modification to my Lamina 45 and that is the thermometer I attached to the Zip pull, other than that the Lamina 45 came ready for adventure straight from the factory.
I paid around $119 US for my Lamina 45, but they are currently on sale as a closeout for around $80 US since Mountain Hardware has come out with a newer version - The Ultra Lamina 45. I recommend either getting a Lamina 45 at the clearance price or being one of the first to have the new Ultra Lamina.
Mountain Hardware's Lamina 45 inside my Oware bivy sack.