The current generation of the bag previously sold as the Neutrino 400. The fill is unchanged — 400 g of 800FP hydrophobic goose down — but the construction moved on: the main shell is now 10D Pertex Quantum (20D stays on the back and footbox) and ISO 23537 rates it comfort 0 °C, limit −6 °C at 870 g.
It is an all-rounder for spring and autumn mountains and cautious low-altitude winter use: the two-way zip vents well and the warmth-to-weight ratio is among the best in the mid range. For frost below −10 °C move up the line; for purely summer use it is unnecessarily warm.