Which servos you use tends to be a matter of personal preference but for the hard facts refer to the following comparison table. Name Torque 4.8v (oz/in) Torque 6v (oz/in) Speed 4.8v (60 degree/sec) Speed 6v (60 degree/sec) Weight (grammes) Hitec HS55 15 18 0.17 0.14 7.5g Hitec HS50 8 n/a 0.09 n/a 5.8g Hitec HS56 14 16 0.12 0.10 10.7g Futaba 3108 17 n/a 0.12 n/a 7.6g Futaba 3107 17 n/a 0.12 n/a 9g Bluebird 371 (frame will need some filing to fit this servo) 21 n/a 0.12 n/a 8g Align KA910001A 14 n/a 0.13 n/a 9g Align KA910010A 9 n/a 0.13 n/a 6g GWS Naro Plus High Power 31 n/a 0.14 n/a 10g GWS Naro Plus Fast High Power 24 n/a 0.10 n/a 10g MX50-HP Micro Pro 23 n/a 0.08 n/a 9g This following table lists a number of gyros that could be used on the X400. Obviously any gyro 'could' be used but I have tried to list here the ones that are small in both size and weight and therefore are more suited to a micro helicopter such as the X400. I'll try to add specifc information for each gyro as and when I get the opportunity to try them and set them up on my X400 test machine. In the meantime you will have to make do with the manufacturers default information and setup instructions. I have only listed heading hold gyros as a way of keeping the list fairly short and comprehensive. I'm sure there are many more than I have listed but I have also tried to keep to main brands in the interests of brevity. Model Manufacturer Weight (g) Size (mm) Instructions Review Head Lock and Standard Dual Rate Align 12 23x21x15 setup instructions In Progress Heli-Hobby Zoom Dual Rate Heli-Hobby 12 23x21x15 setup instructions In progress GY240 Futaba 25 27x27x20 manual GY401 Futaba 30 27x27x20 manual 560 Micro CSM 11 24x24x20 manual 420 Micro CSM 11 24x24x20 manual LW 200 CSM 8 30x30x12 manual PG-01 Pro GWS 16 26x26x27 G490T JR tbc tbc G410T JR tbc tbc G460T JR tbc tbc