I wear beanies during the winter but these are the first summer beanies I've tried. Not knowing the difference, I bought 2 of the Mason LW (black and grey) and 2 Forte LW (navy and California) - couldn't resist the price at the time, at 30% off. In retrospect, it seems obvious, but the Mason is definitely the lighter and more suitable for summer of the two styles. The Forte LW has more of a traditional knit or cabled weave, compared to the finer, less visible weave of the Mason LW. But both models are high-quality hats and wearable in a variety of different climates and can be work either folded or with more of a slouch (unless you have a very large head). I'll probably end up wearing the Masons primarily for summer and the Forte LW's in the winter, as they are much softer and more breathable than my old winter beanies. Just a note on the color of the Forte LW California - mine is slightly different than the shade of blue shown on the website - in real life it seems to have a slight almost teal hue to it - but I suppose that could vary from hat to hat. K&F seems like a great company with excellent products - I wish they'd bring back their workout beanie, as I would definitely buy it.
This beanie is great for the price and quite comfortable. The fit is perfect for me and has just the right amount of "bagginess." Highly recommend.