All connection systems work with one another via the patented dual bridge system, which accepts the same push-in jumpers and accessories. This terminal block system offers users flexibility and savings compared to buying and storing accessories for four technologies. Major components in the standardized accessory system include: flexible bridge system, which enables chain, step-down and skip bridging via two bridge shafts in the middle of the terminal block; modular testing system, in which each position can be occupied by snap-on single plugs or by assembling modular test plugs; and a standardized labeling system.