The Racerstar AirA 2508 motor is a brushless quadcopter motor sold under the racerstar brand but made by T-motor. This motor has a broad stator and tall height matched with a relatively low kV making it an ideal option for 6 or 7 inch quadcopters running 5-6s.
Up until recently there were few large stator motors available, typically the largest we saw on long range 7 inch rigs were 2208 (MB Primo). In fact for this reason I chose 2306 when I built my long range rig here. Although light, the disadvantage with the relatively small stator given the large and heavy propeller it needed to spin was poor control over the prop and a tapering off of power in the high throttle range along with a large increase in current draw (with no output benefit). This resulted in the quad feeling sluggish which I thought was just the accepted norm for a 7 inch quad.
Now there are a lot more larger stator motors around with wids of 24mm right up to 28mm and heights of between 6 and 8mm that are much better suited to 6 and 7 inch propellers. I chose to try the Racerstar AirA motors on my 7 inch build because they have a great price to quality ratio.
The "Air" sub brand from t-motor usually signalled a lighter weight price competitive motor and it is the same here. Retail on this is $20 each or $70 for 4 although they've been as low as $12 on sale. For this you get excellent t-motor build quality that cannot be compared to regular racerstar motors but not the titanium shaft, single strand windings or super strong 7075 aluminium bell of the much more expensive motors. I don't find these especially important though and many tend to agree which is why we see 'budget' lines of premium motor makers (like the Emax Eco) doing so well in the market. Motors for 6 and 7 inch quads especially don't need these super strong materials because they don't tend to be crashed as much given they are typically used for long range flights rather than freestyle. Oh, big 9mm bearings mean smooth operation and good durability too.
Summary: Great quality to value ratio, similar to the Emax ECO in value proposition.