I purchased this wire set as an upgrade for my Echo1 ASC (SCAR-L). As with the reviewer above me, my gun and gearbox is physically identical to his for all intents and purposes concerning this part. From my experience of installing this part, I can say that the fitting is actually spot on. I did not have to cut off any pieces from the trigger housing. However, there is one single hole that threads into an extrusion on the gearbox, and is also where the single screw should be installed to secure the housing. The actual hole on the trigger housing was a bit small for my gearbox. This was easily remedied by drilling it through with a slightly bigger drill bit. After that slight modification, everything fit into the gearbox like a glove. Two screws with different diameters came with the package. I was able to use one of those two to secure the housing without any problems.
I have to say that the quality of the wires is really good. There are three portions that are reinforced with shrink wrap for where the wires exit the gearbox - the rear and also the 2 wires that go to the motor. Though the wires are very high quality, they are also very stiff. You should take care when contouring the wires to fit in the gearbox canals as to not pinch or crease them. I did not have any problems with the motor contacts. When you first receive this product, the motor contacts will be completely straight, though they are normally bent 90 degrees when used with a gun. Like the wires, they are very stiff. I suggest being careful and having some patience when bending them, and to also avoid using any tools to do so, as this might puncture the protective shrink wrap. I would suggest to bend them with only your fingers.
One final thing that I ran into concerns the actual contacts on the main housing. In the main housing, there are 2 silver prongs where the smaller moving contact is supposed to meet to complete the circuit. During normal operation, whenever the trigger is pulled, the trigger pushes the smaller contact into the 2 silver prongs and the gun fires. When I received my part, I found that the 2 prongs were actually too close to eachother. This caused the smaller contact to become lodged between the two prongs and become stuck there, even after releasing the trigger. I was fortunate that I tested pulling the trigger before closing my gearbox and hooking up a battery, or else I would have been stuck with a gun that wouldn't stop firing even after letting go the trigger! This was easily fixed by using a pair of pliers and gently prying the prongs apart a little. I suggest that users test if this happens to them before attempting any sort of fix.
-Great and sturdy wire quality
-The only wire set on airsoftgi that is wired to the rear and also has a Deans connector
-Slight modifications are likely required (as with all aftermarket upgrades)
-The rear wiring where the Deans plug is may be too short for most AR builds. For my specific SCAR, it was fine.