I bought this cheap $1 kit from eBay of small pieces of silicon rubber shaped to fit into all the port openings, e.g. USB port, microphone socket, Thunderbolt ports etc. Before installing, it occurred to me to ask whether these ports are actually needed for air-inlets when the fan is in use, or whether the air comes in through other inlets. I wonder if using these type of silicon rubber seals - which are intended to minimise the ingress of dust - would cause over-heating. I heard that build-up of dust inside the computer, over the years, can result in damage to the motherboard and other parts. Then again, if air can enter through other inlets for cooling purposes, then it means dust would be entering those other inlets. I'm now questioning the benefit of using this kit. Besides, it's only $1 per kit, not a great loss.