The body is a conventional, but light, unibody construction, with (detachable) front and rear subframes. The MX-5 also incorporates a longitudinal truss, marketed as the Powerplant Frame (PPF), providing a rigid connection between the engine and differential, minimizing flex and contributing to responsive handling. Some MX-5s feature limited slip differentials and anti-lock braking system. Traction control is an option on NC models and standard on ND models. MX-5s weigh slightly over one tonne. For example, in 1994, the very rare optional Spec C package included the desirable limited slip differential.