If early cropping is you are after, then DuraLight Thermic is what you need. The lower the number in the infra-red transmission data then the more heat the polythene retains. This retains the heat at night so that not only do you get more degree days into the crop but there is also less condensation and therefore disease.
The optical spectrum is excellent in the UV and PAR wavelengths so that the UV is also helping with earliness, brix, anti-oxidants and shelf life.
Mechanical strength is also extremely high, being stronger than many films which are thicker.
It is also diffused so that scorching is reduced and the plants photosynthesise better.