My Dad had one of these EDZ Underlayers, and I stole it from him. This little jacket is just fantastic at what it does, in my opinion, so I eventually bought one in my size and gave his back to him. Even at the slightly ridiculous £40 price tag, I thought it was worth it.

My jacket and one-piece leathers both have excellent ventilation, which I like. However, in cold conditions, I don't like carrying the thermal linings they came with. They are bulky, taking up too much room in my kitbag, they change the sizing when fitted, and are a pain to fit at the roadside.

Frankly, I can't be bothered to carry around three different layers in my back and adjust according to prevailing weather conditions.

Now, I can just wear a base layer, and perhaps a loose-knit woollen top under my leather. When it gets a little chilly, I just slip this on under my jacket, and instantly the air doesn't flow through the jacket anymore, making it very snug when the wind temperature drops. It's breathable, too, which means it is very comfortable for long periods, even if it gets hot and I can't be bothered to remove it again...

It is incredibly thin, so you won't notice it at all. The thing I particularly like about it, compared to similarly good products designed for cycling and running, is the fleece collar. This dramatically reduces the air flowing through the neck of my leathers and down my back, so in cold weather, it really makes a difference. If you want the air down your back, you can simply unzip it and fold the collar down.

There are certain items I consider essential and won't leave the house without. Along with my clear visor, my V2 Sponge, and my Motrax Guvnor Disc Lock, I simply have to have this as part of my riding gear, regardless of where I'm going.

It does cost £40, which is a lot for something that weighs only 90 grams. Buy one, however, and after a couple of weeks of using it, I defy you to leave the house without it.