The Gateron Ink Black is essentially a Gateron Black with a transparent, smoky housing and a black stem, and is highly regarded as one of, if not the most smooth MX-style switch on the market, rivaling that of Zeal's Tealios V2, and the Vintage Black.
The Ink Black is a fairly medium-weighted switch, requiring 60g of force to actuate and 70g of force to completely bottom out. My personal preferred weight for linear switches is anywhere between 62g to 67g so the 60g of actuation force is very welcome.
I personally like to use my linear switches lubed, but the Gateron Ink Black is one of those switches that doesn't require that treatment to be a smooth switch. It's a fantastic switch at stock, and is probably one of three switches that I'd consider using stock, next to the Tealios V2 and the NovelKeys Cream. The Gateron Ink Black is super smooth even without lube.
With that being said, I still lubed my Gateron Ink Blacks with Tribosys 3204 as I felt that it didn't require thick lube like Krytox 205g0, and it made it even smoother. I did heavily lube my switch, but it did not interfere with the travel, actuation, upstroke, return, or keypress of the switch in any way, and I prefer heavily lubing my linears as it ensures 100% smoothness. Again, not that the Ink Black needed that in the first place, regardless.
In my time scouting the switch market, I can find Ink Blacks for around $0.75-$0.80 a switch, which is fairly expensive considering the other offerings on the market, such as regular Gaterons, which can retail for as low as $0.30 a switch. However, I am confident that expending a bit more for the Ink Blacks will work in everybody who is considering a linear switch's favor, as the smoothness - once again, even at stock and unlubed - is rivalled only by the most elite switches such as the Tealios V2 and the Vintage Black - and those go for $1+ per switch each for what I can perceive having using Tealios V2 extensively as minimal improvement.
In fact, since using the Ink Blacks, they've become my top 2 linear switch next to the Tealios who edges it out as a close winner. The Ink Black is smooth in every regard and the spring is really high quality. The spring feels robust and full which gives the Ink Black an ultra satisfying keypress travel. The Tealios on the other hand has a fairly hollow spring which is susceptible to pinging.
If you're in the market for one of, if not the smoothest, linear, MX-style switch on the market for under $1 per switch, you cannot go wrong with the Ink Black. Ultra smooth stem, silky smooth housing, satisfying spring sturdiness, and excellent lubing capability, making it a solid linear switch.