A retainer lens of shape and dimensions configured to be releasably secured in the front opening of a face plate or helmet has a window opening configured for positioning in front of the eyes of a wearer of the face plate or helmet. In one embodiment, the augmented FC frame format is modulated on a carrier signal and the frame includes: a start-of-frame field; a supplementary header field that follows the start-of-frame field; a frame header field that follows the supplementary header field; a cyclic redundancy code checksum field; and an end-of-frame field that follows the CRC checksum field. The free-floating ball is seated and seals the liquid fluid within the check valve housing against leakage when the bailer is retrieved from the body of liquid fluid. The system has an actuator operating the multi-rope lever system. Grooves are provided in the region of the tooth gap base andor on an inner surface of the flange facing the toothing for feeding away a lubricant. The instruction also limits the amount of data to be prefetched.