Fischer elektronik 41 cool rail heat sinks fischer elektronik sk 189 50sa the fischer elektronik 35 cool rail 415 x 50mm heat sink has been manufactured to a high standard using raw degreased aluminium and is ideal for plastic transistors and relays the effective heat dissipation make it ideal for a wide range of applications fischer elektronik sk 189 50sa cool rail 415 x 50mm heat sink 35cw