This is the ProModeler DS845BLHV servo. It's one of a series of three servos, this one, the DS845, plus the
DS635 and DS1155 where the basic differences are the motors and gear
ratios - otherwise they're like three peas in a pod!
It's of a size and shape similar to other standard-size servos meaning it features conventional beam mounts so it's designed to be installed with vibration isolating rubber mounts, but it sports a beefy 15T spline (versus the smaller conventional 25T spline output shaft). It has a brushless motor, and is equipped with steel gears, dual bearings, and is built within an bronze-reinforced all-alloy case. What's more, it meets three MIL-STDS . . . servos just don't get any better.
Basic specifications
- 845oz-in of torque
- 0.06sec/60°
There's nothing else as strong and fast the DS845 (not at any price). How's it match up to a well-regarded competitor like the Savox SB2290SG Monster? Theirs goes about 700oz-in and 0.13sec/60° . . . not as strong or fast.
And with regard to how the build qualities compare? Well, you decide . . .

Gears

Bearings
The DS845 bearing on the left as compared to those in Savox SB-2290SG
is 25% larger, rated ABEC-9, and shielded. Theirs? Sorry, they don't
say.

X-MAXX
With regard to mounting the 2290SG within an X-MAXX, you'll resort to the plastic Traxxas #7749 adapter vs CNC-machined aircraft aluminum solution.

Anti-vibration
Part of what makes the ProModeler DS845BLHV better than competitors is that unlike hobby-grade
servos, it's built to meet military standards (and subjected to these tests).
MIL-STD-810G-Part 16
- Shock - Test Method 516.6
- Vibration - Test Method 514.6
- Rain - Test Method 514.5
ProModeler servos are expressly designed to survive the abuse of the real world outside of modeling . . . and it's another ownership
consideration.

Power
Last thing is this, if you're wanting this for a rig instead of an airplane,
heads up, servos like these won't run on the typical BECs they give
away for free on some import ESC. Kindly trust we know more about
powering servos than someone named rocknutz
on
a Facebook group and forum, please.
Anyway, while packs aren't really
our line of business, we offer several dedicated 2S packs ranging from
850-6000mAh plus an excellent standalone BEC. This is so you can run your servo
and be happy. Just refer to the first pull-down menu above. Oh, so you don't
want to do this? OK, but please don't say we didn't warn
you, eh?
Magic
So where's the magic in this servo? it's in the design of the gear
train that allows us to stuff much larger gears into a standard size
footprint . . . and it's patent pending!