| HACKER Gear Sets |
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| SPRINT 200 GEAR SET 1:57 Planetary gear box for 200 size electric motors (such as Hacker 3101). For indoor or slow flyers. Uses a 1:5.7 gear ratio. |
SPRINT 280 GEAR SET 1:4.5 Planetary gear set for 280 size electric motors. Fits Hacker's 3102 perfectly. Gives a 1:4.5 ratio. |
| SPRINT 280 GEAR SET 1:4 Planetary gear box for most 280 electric motors. Uses a 1:4 gear ratio. |
SPRINT 300 GEAR SET Planetary gear set for 300 size motors. For 1:3.6 gear ratio. |
| SPRINT 400 GEAR SET 1:3.6 Planetary gear box for 400 size electric motors. Uses 1:3.6 gear ratio. |