This lovely little cable allows you to bridge the gap between the korg / yamaha / moog gate world and the eurorack (more common) gate world.
for some mysterious reasons, korg, moog and yamaha decided to go their own way. so this little cable contains a few components inside the the 6.35mm jack plug that converts v-trigger signal. into s-Trig signal.
With this cable this incompatibility becomes a problem of the past and you can enjoy triggering your korg ms-20, moog phatty from your eurorack modular system.
there are more complete modules out there that to that on both way (from and to ms-20) and also do the cv conversion : [LINK] . but that come at price !
in short, it does the job well, and is much cheaper than the module mentioned above (for less functionalities, that is true). that being said, looking at what is inside the cable, 25euros is quite expensive, but i suppose that is the price to pay for such a nice product.