TLDR: This is the sportiest 0A yoyo produced to date. Pros: It’s snappy, powerful (but not overly powerful), and a stall machine with good control for flips and varials. Cons: It could have maybe benefited from 1-2 grams more weight and it is less comfortable on the catch vs. the RBC and Weekender. It is slated to release on March 8th at YYE.
Disclaimer: I am not affiliated with MK1 or SW, I bought this yoyo with my own money and @MarkD was kind enough to send it to me ahead of release so that I could write this review. He was also generous by unhalfswapping an orange/blue yoyo so that I could have a full blue one to match my set. 
If you want a full orange one, Mark may have one kicking around. 
The Harbinger was originally @Glenacius_K’s first release of handmade wooden yo-yos under his brand, Spinworthy yo-yos. It has since become a flagship model for SW with its characteristic rounded wing profile and large diameter to a comparatively narrower width. This aesthetic then influenced many of Glen’s designs following and it is one of my favourite features of SW designs. I was excited to hear that MK1 and SW were collaborating on an aluminum Harbinger.
The dimensions and profile of the Harbinger are pretty much identical to the original SW design.
Despite the Harbinger’s namesake, it’s not the first collaboration between MK1 and SW, but let’s also hope not the last. Their first collaboration, the RBC (Red Blood Cell), was a massive success, with 2 production runs completely selling out in just over a year. In addition to its unique shape and elegant seamless cap design, what was truly innovative about the RBC was its use of the MR85 bearing, which had not been previously used in a yoyo design. With an outer diameter of 8mm, Glen chose to try this bearing to capture the feeling of his 8mm fixed-axle yoyos in a modern responsive design. Moreover, a smaller bearing size allows the string to wrap closer to the centre of gravity of the yoyo.
This affects 0A play in 3 ways:
- There is a higher RPM at the point of contact with the response, meaning that the string wraps tighter and with more snap, allowing for better returns even at low yoyo RPM.
- Compared to A and D bearings, there’s a smoother transition between the throw and spin, which causes less of a thud at the bottom of the string.
- Overall better stability in stalls.
It is my opinion that the MR85 is the best bearing option for modern responsive yoyos. 
Overall the RBC guts have perfect proportions between the gap size, response pad size and bearing diameter size which allow for a clean throw with minimal kick back (a.k.a. loop up). All of this goodness has been carried over to the Harbinger.
Some of you may know that I have a well-loved RBC that I play every single day. The RBC is a loving but unforgiving beast. It is comforting in the hand and very capable, but you better be throwing clean or else it will punish you mercilessly. And I honestly love that about it, but it can be frustrating for learning some advanced stall tricks.
I will briefly mention that Mark has also helped design another MR85 yoyo that is out in the world, it is called the YT Origen. It’s a fun yoyo, that looks pretty, and is also surprisingly inexpensive. That said, I wouldn’t recommend it for 0A simply because its walls aren’t high enough to stick stalls with reliability. Nuff said.
All of this is to say that while I anxiously awaited the arrival of the Harbinger, I was anticipating a sportier 0A setup that performed better at stalls than all previous MR85-yoyo options. And spoiler alert… That’s what we got.
All 3 yoyos to currently have MR85 bearings: My well-loved navy RBC (left), the Harbinger (middle) and the YT Origen in blue (right). Note the Harbinger is actually slightly narrower than the RBC but has a larger catch zone. Also note that the Origen has no wall remaining past the string wrap, this (plus it’s wide rim weight) causes it to struggle with stalls.
Overall design specs:
- 47.5g (approximate)
- 32.8mm wide
- 58.5mm diameter
- Gap size: 2.4mm
- 6061 aluminum alloy
- MR85 bearing
- 12mm m4 axle
- RBC Pads
- Price: $60 USD
Aesthetically, the Harbinger is perfection. I had seen pictures of the prototype a while back and loved the profile, but I wasn’t keen on the cup and inner rim design. When I saw the final design, I was in. I love that classic SW wing profile, the squared off axle posts and the angular cuts in the cup and rim. This blue is awesome, so rich and deep, almost purple but not quite. All the release colours look awesome, if you haven’t seen them yet, check out the MK1 thread here and here. I also know that Mark put a lot of work into a unique new packaging design for this yoyo. I’ll let you discover this on your own, but I’ll say that it is sleek and really impressed me!
While the Harbinger prototype was made in 7068 aluminum, Mark and Glen ended up on a 6061 design, principally to keep the cost and weight down. At $60, the Harbinger is much more accessible than the $85 RBC price tag. I personally like both materials and find that each has its advantages. The Harbinger feels great in 6061 with a nice lightly blasted silky finish.
I was a bit surprised to find that the gap width in the Harbinger is 2.4mm (same as the Origen) vs. the 2.3mm gap of the RBC. This was likely chosen to handle a bit more string layering and a wider variety of string choices. This wider gap still plays great, but I recommend using thick string to eliminate a bit of kickback and keep the throw true. The included OT fat string works well. Twisted Stringz X-tra thick is also keeping it toight. 
Note: With the RBC I recommend using a thin string.
Here is what you are really here for - How does it play?
One thing that some people say about the RBC is that it is very (overly?) snappy and powerful in its standard bearing format. The Harbinger seems to address this as it is still quite powerful, but the larger diameter slows it down a bit, making it feel more manageable and controlled coming in and out of stalls. It is the closest feeling to playing a fixed-axle with a bearing yoyo and certainly accomplished this goal better than the RBC. I actually prefer to play the RBC modded as a fixed-axle, but so far I prefer the Harbinger in its stock setup. The Harbinger’s high walls and comparatively narrow profile mean that it sticks stalls solidly. It varials and flips nimbly and with oodles of control. The winged profile gives it plenty of catch zone, making it easier to land that trick you’ve been grinding.
Despite being almost the same weight as the RBC, to me it feels lighter in play, likely due to the shape and proportions of the design. This is where I feel this yoyo lacks. As much as I like to keep my 0A yoyos light, I think the Harbinger could have benefited from a little more weight - likely 50-52g would have felt more substantial in play. But that’s just my preference. I also don’t find the Harbinger to be very comfortable in the hand. The profile is nicely rounded including the rims, but the rim thinness causes pressure points on the hand during catches. Again, this is likely just a preference for me, I’ve beat up my hands over the years with archery and rock climbing, and now also have some pain issues. So I think I’m getting to be overly picky about how a yoyo feels in the hand. 
Overall, I have really been enjoying playing the Harbinger. This is a very different beast from the RBC but with the same guts and soul. This one is a true high performance 0A player and I highly recommend it for anyone’s arsenal. That said, I will admit that I still prefer the RBC as my daily carry and player. This is almost exclusively because I find the RBC to be more comfortable for my hands.
I’m happy to answer any additional questions. I would also love to hear what you think once you get your hands on one! Have fun friends!
