The spring terminal blocks were designed mainly for jointing control circuit wires in 0,2 mm2 - 6,0 mm2 cross-section range in good quality, quick and reliable way. The terminal block can accommodate unprepared rigid wires, or twisted or flexible wires equipped with cord-end terminals or male lugs. The highly heat resistant, strong, self-extinguishing (according to UL94-V0) polyamide plastic house with good electrical parameters – witch contains the electrical elements - , is shaped in a way to permit the terminal block to be fixed onto mounting rails according standard EN 50022 („hat” or „C” rail).