First is the Active Noise Cancelation mode that blocks out all external noise so you can focus on the in-game happenings without getting distracted. There's also a Transparency mode for when you want to let some sound in. This mode isn't as appropriate for gaming, but it does a good job of keeping you aware of your surroundings when you're out and about.
The device in question is the MX Master 4 mouse, which is a delight to use. As with its predecessor and others in Logitech's range, it is ergonomically sculpted and fits a user's hand. However, in a step backward, most of the body lacks the soft-touch, rubberized plastic we saw on the MX Master 3 and 3S. Initially, the MX 4 looks more like an evolution of what came before, the MX 3S.
The mechanical keyboard world has undergone a renaissance. Thanks to increased competition and commoditized tech, features that used to be exclusive to limited-run DIY boards in the $300-plus range just a few years ago are now available in prebuilt boards in the $100 to $200 range - sometimes less. The DIY kit builds, limited-run group buys, and boutique boards made by artisans are still innovating and pushing boundaries, and they're great if you're looking for something extra adventurous or very specific.