A high resolution energy-selecting electron beam apparatus and method for improving the energy resolution of electron-optical systems by restricting the energy range of admitted electrons, and optionally also for improving the spatial resolution by correcting chromatic and geometric aberrations. A reticle-masking blade is supported with a reticle-masking blade carriage assembly. A lock mechanism locks the variable mechanism so as to maintain the valve timing of the cylinder group at a lock value. As a result, the access control capability of a wireless local area network is enhanced and the working efficiency of the network is improved. The elongated members are curved to position the points of contact with the desired orientation. The support material is of the following general formula : .