This latest iteration of the BOX Silent design represents a genuine improvement over previous versions, as well as a solid entry to the space in general. Like all BOX switches these are IP56 dust and water resistant and feature an enclosed set of contacts, and like the other silent ones, these are also North-facing-friendly with GMK and other low-profile caps.
In terms of noise level, they're about on-par with basic Gateron Silents, with less scratch in the sound and feel. I'd make the same comparison with the previous generation design, as well. These are the smoothest circle-shroud BOX switches I've used so far, and they're plenty quiet for office use. Compared with many other dampened switches, these feel a bit more crisp at the cost of slightly more noise; if you're familiar with Gazzew's silents, these are at the opposite end of things.
"Thock" is the hobby's most over-used onomatopoeia, but it's also probably more accurate in describing this switch (and a few other dampened ones) than any of those loud and clacky long-pole tactiles. There's the gentle swish of the stem as it goes down ("th"), and the muted plop ("ock") of the broad stem foot against the bottom pad. Gentle thocks.
Only audible in the least forgiving of metal-based builds (or right next to your ear), there is some slight spring ping with these. Unless you're building them into a CNC'd case with a brass plate, chances are you won't need to tune these at all - and if you are, just bag-lube the springs and you're good to go.
My only request to Kailh would be to make a few more spring weight options available for the switch, kind of like Zeal does with Zealios and Zilents. While I think these have a good weight for a large portion of typists, they're just a little light for my preference, and I'd pick something heavier were it available.
When it comes to buying from SwitchCaptain specifically, I'm not sure I've ever felt so considered as a customer buying switches before. I'll explain: SC gets their switches directly from the manufacturer, includes proof in the package, and tracks each and every pack with a serial number for quality control. They're packaged in tins that not only look pretty cool, but also do a great job of protecting the switches in transit - no mangled pins here. They even come with a basic switch puller in the tin, just in case you don't already have one. Nice!