Arctic's MX-4 thermal compound has proven itself well in the DIY space, but it's been around for quite some time and seemingly, like everything in tech, in need of an update. So in comes, low-and-behold, the MX-5. The MX-5 thermal paste hasn't been officially announced yet nor is it listed on Arctic's website, but hardware detective @momomo_us found the compound listed on Amazon UK paired with an informative description.
Although full specifications aren't available at this time, what stands out most about the description is the paste's durability: it's alleged to last for up to eight years once applied.
Of course, enthusiasts generally change CPU multiple times in eight years, but MX-5's alleged durability can be extremely helpful for use in laptops, GPUs, or that PC you're building for a relative. Its not clear what the MX-5's thermal conductivity is, but if Arctic's historic products are anything to go by, it should be pretty good.
MX-5 is metal-free and non-conductive, so it's also safe for use on GPUs without needing to worry about over-spilling on the area around the GPU.
A single 4g tube of paste (enough for well over a dozen builds) is listed on Amazon UK's site for £13.59, which translates to about $18.50. That's probably pre-order pricing though, and it will likely drop in due time. According to Amazon the MX-5 thermal grease will be released on March 15 2021.