Wieland fasis duo feed through din blocks wkfn d1235 32a41a bluegrey wieland 5670650556 wielands blue fasis duo feed through din block wkfn 6 d1235 is a terminal block for mounting onto a ts 35 din rail and has been given an approved atex rating for use in various zones the secure and maintenance free tension spring clamp remains simple to operate via a standard screwdriver which can be held securely in the terminal for optimal handling while connecting wires the block has a 41a