Back in the dinosaur days, there was an advertising campaign for helmets that billed them as "courage for your brain." Courage is fine, but what's even better is straight-up armor, and the best brain buckets these days use MIPS: multi-directional impact protection system.
MIPS is basically a helmet within a helmet. The outer part rotates around the inner part to dissipate the force of impacts at an angle, which are most impacts for heads that are moving. Giro has always been a leader in helmet design, and so no surprise they've got a bunch of MIPS helmets including three mountain bike models.
The Giro Chronicle is the middle of the three. It's a great helmet, providing maximum protection with minimum fuss. The liner is comfortable, the adjustments easy and the goggle compatible visor has three different positions: all the way up for maximum visibility and cooling, all the way down for shade. The 14 vents provide generous airflow without sacrificing protection, and the chin strap is a set-it and forget it design.
One thing about the Chronicle that we really appreciate is how far down the back of the helmet extends. It provides a lot of coverage for the tender part of the base of your skull, something not all helmets do. If it's time to upgrade your melon cover, definitely go MIPS and definitely put the Giro Chronicle at the top of your list.