Great disc, incredible plastic. Much flipper than the flight ratings, my go to straight driver for 325-357 foot shots. Careful in the wind 

This is the first distance driver I've ever loved. I've never been able to really like any drivers, and I've tried quite a few. The feel of the disc combined with the best feeling plastic on the market make the best driver I've ever used. 
 

I own two different Grym X's. One in K1 plastic and one in K1 glow. The glow plastic is slightly softer and grippier and noticeably more understable. The K1 is firm but grippy and much more stable, but it still has a little bit of turn if thrown flat or a little flip when thrown on hyzer. 
 

I've been searching for a true go to distance driver that I trust for a very long time without success. The moment I felt the Grym X, I knew that search was over. The way they fly is only second to how they feel, and I can now grab a driver out of my bag and be confident in what is coming out of my hand. 

I throw around 300 feet with a nice throw of an 8 to 11 speed disc (I rarely throw higher speeds). I have a Titan (over stable ten speed) and wanted something with a bit more reach. I like Kastaplast and reviews were saying it was much more understable than the numbers. I can definitely agree with the people who compare it to a Wrath. Even with my arm speed this thing is much less stable than I wanted it. That being said it is an amazing disk. I tend to use it in the open when I want confidence it will finish left (RHBH) but I also want to reach my max distance.

Very similar to a slightly seasoned destroyer. But in the goodness that is kastaplast plastic. Highly recommend. 

This is a great first distance driver. Regardless of the numbers, it flies like the 10 speed version of a wraith/destroyer. A power thrower will find that this is too flippy. But for most players, this is a pretty reliable disc. Very similar to an Innova orc, maybe slightly easier to throw.

I can also report the disc being very understable. However, it's great at being what it is. It's my longest driver.

I bag several pharoahs and an x-cal. Was looking to fill a slot in between with this disc and was very disappointed. Love k1 plastic so i bought one at 171g. It's so flippy. Threw it in my bag and brought it to 2 courses. Tried to tee off with it a few times and was astounded by the amount of turn it got for a 0, 3 finish. I put it on hyzer, expecting it to hold a hyzer line but instead it would flip to flat (or further) and just sail forever and overshoot the turn in the fairway by a mile. "Maybe I need some field work with it?" I thought and did just that. On a level release with no wind or a tail wind it can completely turn and burn, anhyzer turns it into a throwler. With about a 30 degree hyzer it flips to flat and goes straight with little to no fade at all. Into a head wind... Damn. Had to put it on like a 70 degree hyzer to keep it from flippy over and the nearly vertical shot feels ridiculous. For reference I throw about 380-420 depending on wind, form, arm condition, etc. Maybe I got a bad mold??? But now I'm hesitant to try another one... Shame, k1 is a buttery goddess.

First off, this is my obligatory nod to k1 plastic: it really is the best plastic on the market. It's worth picking up a Kastaplast disc just to try it out.

On to the disc itself. I was looking for a disc to fit in my bag between a Zeus and an ESP Force. After a lot of research (and a bias for bagging more k1) I settled on the Grym X. I could not be more pleased with what I got. The Grym X flips up to a slight turn before fading with a forward finish. It's the perfect stability for long straight shots that don't risk turning over too far and leaking right. I have two, both max weight in white k1 plastic. For what it's worth, the color does seem to affect stability for this company. The new runs of this disc are printed with 12/5/0/3, but mine have a smidgeon less HSS than an ESP Force, so I've marked it as a -0.5 turn.

One final note: The 2019/2020 runs of this disc in the k1 glow plastic are reported to be very understable, counter to the usual tendencies with glow plastics.

I like this disc quite a bit - K1 as always feels fantastic in hand, and the disc has become pretty reliable for me... reliably stable, that is.

For reference, I throw about 350 consistently, 400 max distance, and this disc is ridiculously overstable for me.  I use it as my longest disc that I need to be super stable and provide skips.  Again - I'm not the hardest thrower, but this this has zero turn for me. I throw things like Wraith's and Destroyer's pretty well and get solid flip up, but this disc feels like a faster firebird to me rather than a Destroyer relative.

Nothing wrong with the disc, but I think it is very mis-labeled and does not fly true to the numbers at all.  More like a 13/5/0/3.5 to me.

Why I like this more than the destroyer:

The weight: typically for Destroyers, the heavier they get, the thicker the rim will be. For me that hinders my ability to keep my grip tight. On the Grym X (i have a variety of weights) the heavier you go the rim thickness is virtually unchanged. My 175 still has that sharp edge that my 170 has. I would argue that because of this one particular aspect it is more predictable/reliable in a headwind...

The flight path: this disc flies pretty much straight on a slight hyzer and then does it's fade at the end. This reliably happens every time for me even when I feel like it was a garbage throw. Throwing it flat, it comes out for the most part as the numbers say. 

But here's the kicker * K1 Glow *

The regular K1 is pretty similar to the destroyer just nicer in my hand because of that blade edge and the plastic is the nicest on earth. But the real fun comes from the Grym X K1 Glow.

For whatever reason glow plastic is pretty much always more overstable. The K1 glow plastic moves this from Destroyer to Ape. The glow plastic makes this disc more like:

13/5/0/4

But because of the mold it feels exactly the same as the regular K1 grym x... that to me is enough to call this a 2 in 1 discs. Learn with 1 disc and have 2 different throws... (obviously you still need to buy 2 different kinds of plastic) also the glow plastic has a lot more skip than the regular K1.

The Grym X is definitely a beefy disc. It felt super nice in my hand.  If you've held any K1 plastic you know it feels super grippy, which I've always been a fan of.  On a good throw, I could get this disc around 300-350 feet, but if I ever released it with a hint of hyzer, it was a goner, dumping off to the left before it got any good distance.  I'd say it probably has more of a 3 fade, and not much turn.  If you have a big arm, this disc could be a sick bomber.  For me, it'll be a good disc to get around groups of trees or bushes on the local rough course.

The first time I saw the Grym X in flight was when I watched somebody with an arm that can whip discs a couple hundred feet further than I can. He threw it in a pretty steady wind and the Grym X seemed to fly forever, and it certainly made a long, strong fade. I was mightily impressed. Then I took my turn. Well, I can blame the lack of wind, or I can confess that my arm is not as strong, but it didn't fly as impressively when I threw it. It is definitely overstable, as advertised. It has a strong fade. Even when I throw it with an anhyzer, it turns right back. I can definitely say that the Grym X is a solid driver for the advanced player, but I wouldn't recommend it for a beginner. If you're a competitive player with room in your bag for another overstable distance driver, then it wouldn't be a bad choice at all. Generally speaking, I'm a fan of the Kastaplast discs. They feel great, and fly true.

The Grym X was a fun disc to throw, and it makes a great addition to the Kastaplast line up. It is definitely as overstable as the flight chart shows, but it goes very far. I felt like it didn't take much to get max distance out of this disc. Also it is much more comfortable in the hand than the original Grym. I definitely would recommend it to bigger arms who are looking for a reliably overstable distance driver