This testimony contains comments from NIOSH on the proposed change in regulations which would allow certain mechanical power press systems to be activated with a presence sensing device. The basis for the change comes from a NIOSH study of experimental variance at Interlake Stamping Company facilities in Ohio. However, the limited operational experience with presence sensing device initiation (PSDI) is a factor which NIOSH feels needs to be taken into account. The proposed standard requires that data be provided on failures of PSDI systems. Four of the five studies reviewed had the subjects begin with their hand at zero velocity. Problems with these various studies are discussed. There is a great deal of ambiguity as to the mean, median, mode, and range of average reach speed values obtained at various conditions. Comments are also contained in the testimony concerning cycle control and control systems, electromagnetic interference, and the need for a hand speed constant.