First introduced by Mountain Equipment in 1989 EXL® technology was designed to provide Extra warmth and Extra loft, it was a simple but groundbreaking innovation to make sleeping bags and clothing as thermally efficient as possible. Elasticated stitching in the lining of a product adds no weight but minimises dead airspace around the body and pulls fabric away from the down allowing it to loft to full effect. This has a marked benefit on performance and extensive testing shows that a sleeping bag with EXL® will be around 2°C warmer than one without it. Whilst sounding like a marginal gain 2°C represents a significant benefit at the lower end of a bags performance range. This can be the difference between recovering and merely surviving whether on long expeditions or a fast moving alpine climb. EXL® remains as relevant to improving insulation in high performance sleeping bags today as it was nearly 30 years ago.