Large models require strong, rigid rotor heads which are designed to cope with the demands of a rotor disc of commensurate size, and are built for mounting on a 12 mm Ø rotor shaft. The only rotor blades you should use are 416/3 or 417/3 (right-hand rotation).The GRP blade holders are extremely rigid due to their high glass fibre content, yet they retain a degree of flexibility. The blade grips feature a 22 mm opening, and are designed to accept rotor blades of this thickness over the whole width and depth of the throat.Other makes of rotor blade - even when they are claimed to be copies of our original blades - must not be used if the area around the blade holder screw is small.The rotor blades with a profile thickness of 14 mm were developed by VARIO specifically to provide flying characteristics with a three-blade head which are similar to those of a two-blade head.Typical applications for this rotor head are models with a rotor diameter of 2500 mm, such as the Mil Mi-2 and Lama. The length of the pushrods between the swashplate and the blade holder arms will vary in length according to the rotor shaft you are using, i.e. you should select the pushrods which are recommended for each model; the same applies to the swashplate driver which is also required.This 3-blade rotor head is designed for use with a model helicopter powered by turbine exclusively.Up to 20 kg take-off weight.