In the past I have only used "Robart" pneumatic retracts however the model has the mechanical retracts already installed. In order to install pneumatics, modifaction to the strut channel and whell wells would be necessary. "Robart" struts and wheel assemblies are not light. I thought I could attach the strut to the strut wire and modify the channel. Then the question arose could the retract servo, retract the weight of this assembl, either statically of dynamically? A pneumatic assembly would negate this issue.