A push button switch includes a base, a locking member received in the base, a push button switch penetrating the base to engage with the locking member, and a lock body. Such orientation and position are on a long term basis maintained steady with respect to a display field. After completion of the solid and liquid component mixing, the bone cement has an initial viscosity effective for manual application or manual injection onto or into a targeted anatomical location, e. The processor provides a communication path between the medical device and the processing device such that programming and instructions may be communicated from the processing device to the medical device and data may be transferred from the medical device to the processing device.