Why does the CoolSmooth take two hours instead of one hour like the original CoolSculpting applicators? Does it not get as cold?

The original CoolSculpting applicators rely on suction to pull in the tissue to cool it and cause the fat reduction.  The CoolSmooth applicator does not have the suction but is applied to the skin of the outer thigh to result in fat reduction.  Because it does not use the suction in that area, the treatment time is 2 hours instead of one.  The reason the CoolSmooth applicator does not use the suction is that the fat of the outer thigh is more closely attached to thigh and is not grasped into a suction type applicator.    

The main difference is that the CoolSmooth applicator has a unique flat design which means it can be used on stubborn fat that can't be pinched. The flat design means that there's no suction applied, but that also means that it requires a longer application time. When you have pinchable excess fat as on the belly or love handles, it's better treated with the suction of the original CoolSculpting applicator. Thanks to the suction with this device, it only requires one hour of treatment time to achieve a great result.

Because the tissue is not as
compressed as in the applicators where it gets pulled in the circulation is
more able to warm up the tissue so it does not get as cold so more time at the
temperature is needed. We did the clinical trial that resulted in FDA approval
for the CoolSmooth and patients were very happy with results!

You ask a very interesting question. To give you some historical context. Coolsculpting was invented by two Harvard dermatologists. I had the good fortunate to be a resident at the time the initial research into Coolsculpting was done at Massachusetts General Hospital. The Coolsmooth applicator actually closely resembles the prototype research device that was used to study the procedure. The other applicators use a vacuum to pull the fat into a hand piece where it can be cooled from both sides of the hand piece so the cooling can be achieved faster than with a flat applicator like the Coolsmooth applicator. To obtain the clinical result, the cooling cycle needs to be longer with the Coolsmooth applicator. 

The concept behind all the suction based applicators is that when fat is drawn into the applicator, it is isolated from the muscle, blood supply and heat, therefore, making it faster to freeze. With the CoolSmooth applicator however, the fat tissue is not isolated. The closer it is to a heat source, the longer it will take to freeze. The extra hour makes up for the fat cells not being isolated, allowing enough time for the cells to become crystalized and damaged.