- This paper provides an insight in heat transfer from horizontal-base pin fin heat sinks in free convection of air. Experimental and numerical investigations are performed with sinks of several bases and fin heights. The sinks are made of aluminum, and are heated using foil electrical heaters. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6.3 software. Sinks with free and blocked edges are explored. The effect of flow patterns on the free convection heat transfer from the sink is presented.