First of all, this overshoe is designed for light and slim road/XC shoes. Bulkier trail-type shoes have a much tighter fit and so if you have a size 42 XC or Road shoe (summer type ideally) then a size Large would fit fine as it does for my Shimano XC1s (it has a bit of give where I can pinch the material). My 43 Northwave Trail-X shoes fit in a size L overshoe but it is a very tight fit, which would be fine for the more simple model of this overshoe with no light but this version with a light at the heel causes the light to turn on and off due to the pressure from how tight the overshoe is. If you want this version, the "Open Sole" version to perhaps wear over trainers or more trail-like shoes then please go for a size up (an XL for example would be better for my size 43 Northwave Trail-X shoes). The material of this overshoe is well made and feels durable despite being so light. This lightness is both good and bad, as the neoprene part of the overshoe, despite being very visable, only makes up 10% of the materials. Compared to heavier overshoes that are mostly thick neoprene this shoe does not keep your foot as warm when soaked, but this is to be expected for something this thin and with a fleece liner on the inside. This overshoe, since it is advertised as "All-Weather" feels like it is intended for cool weather to above-freezing cold weather in light rain. If you expect to be soaked, like cycling in torrential rain, then a thicker mostly neoprene overshoe is a better choice. The light is really good and the main reason I bought this overshoe. It is good at keeping you visable and a moving light at the back of your heel is a good way to get people to notice you, and because the lights are on your heel they make you look wider than if you only had a light on your seatpost. I'm all for being lit up like a christmas tree and more lights hopefully mean more visable and mainly, more noticable! Overall, this is a good overshoe that is mostly true to size with summer and/or lightweight cycling shoes (road/xc) but if you want to have the overshoe not fit too snuggly on bulkier shoes then go a size up from the range where your shoe size fits. Since this overshoe is on a sale I think it is definitely worth the discounted price!