A great portable (12v) fan to cool your telescope's primary mirror

Not being totally satisfied with the standard muffin fan that is commonly used to help cool the primary mirror on most truss-tube dobsonian reflectors, I searched the internet and found a fan that really works well. The great thing about this fan, aside from pushing lots of air (up to 1000 cfm) is that it operates using a 12v power source. I have used this fan at remote sites a couple of times now and have found the fan to reduce the amount of time it takes to cool the fan by more than 50% as compared to using the muffin fan alone. Using the muffin fan takes about 3 1/2 to 4 hours (or more) to cool the primary from about 75° - 80° F down to ambient (approx. 50° F). Using the Endless Breeze fan cuts this time to just under two hours. Please note that these figures are not exact and are only approximations.

I mount the fan on my 12v Power Supply which helps direct the flow towards the center of the primary. I usually have the fan running while collimating the telescope and while I'm waiting for darkness to fall.

Left hand picture shows the fan with the 6 foot power cord. Right-hand picture shows a close-up of the power/speed switch. The unit has three speeds (low, medium, & high) (0 = off) although I just use the high setting. I purchased this from Fantastic Vents.