Fischer Elektronik Cool Rail 97 x 25 x 50/75/100mm Heat Sinks – Fischer Elektronik SK 72 50 SA, The Fischer Elektronik 2.4° Cool Rail 97 x 25 x 50mm Heat Sink has been specially developed for semiconductor-design TO 3. The effective heat dissipation makes it ideal for a wide range of applications. Fischer Elektronik SK 72 50 SA Cool Rail 97 x 25 x 50mm Heat Sink 2.4°C/W