The invention relates to a connector for joining two conductors, including a first semi-housing and a second semi-housing that can be moved from a position in which said second semi-housing is in a pre-locked state with the first semi-housing into a final locked position. For example, this can be used when an array of focusing elements is used in a projection system of a lithography system. The stacked layers can include a first-metal-containing material such as Al2O3, andor AlN overlaid by a second-metal-containing material such as TaN, TiN, WN, MoN or their respective metals.