Muller operating hours counterr panel mount 7 digit muller bw4018 the muller bw4018 is a reliable 230v ac operating hours counter that records operating times in electrical systems machines heaters etc the counter is easy to install using the quick fix retaining clip and the easy to connect screw terminals are accessible from the rear mounting in the panel requires an aperture of 45 x 45mm the large 44mm white digits and red decimals are clear and easy to read muller bw4018 operatin