Gears for the Berg V1.
All 5 gears are included. You will want to purchase 2 of these for an entire car, 1 will do just 1 axle.
Standard ratio will net you anywhere from 27:1 ratio with 20t pinion to 46:1 with 12t pinion.
Lower ratio will net you anywhere from 34:1 ratio with 20t pinion to 57:1 with 12t pinion.