This geardrive has a special 8523 motor which is 23mm long compared to the standard 20mm long ones. The shaft is also 1.5mm so you will either need to drill out the prop hole to 1.1mm or use a 1.5mm prop adapter on the shaft.
MicronWings Test Data
 Propellor |  Volts |  Amps |  Thrust |  Notes |
 GWS 3020 |  3.7 |  2.15 |  35 grams |  Sustained |
 4.0 |  2.3 |  40 grams |  Sustained | |
 4.2 |  2.47 |  45 grams |  Sustained | |
 90mm eProp |  4.0 |  2.56 |  53 grams |  Sustained |
 GWS 4025 |  4.0 |  3.95 |  65 grams |  Sustained |
 GWS 4040 |  4.0 |  5.12 |  56 grams |  Sustained |
 GWS 4530 |  3.7 |  4.4 |  70 grams |  Sustained |
 4.0 |  4.9 |  82 grams |  30 seconds till overheat | |
Note: You will need a 1.5mm Prop Adapter for this geardrive
The geardrive is supplied with the base plate fitted but not glued in place. If you intend to use the base plate, with the base plate inserted, add a little superglue to the seam where the base plate and the gearbox hub meet to secure it in place.