A comfortable blade for flat surfaces - easy to peen. Length 50-85 cm.
If you're not used to handling a hammer, this is the blade you should choose. The steel is a bit softer, which will be noticeable during peening. However, the sharpness holds up extremely well.
A light and elegant scythe blade. The lightest of them all. The hooked shape of the blade allows you to take more grass per stroke while maintaining a good cutting angle against the grass. This blade is slightly more suited if you don't want to cut as wide but still want the ability to go a bit deeper with each stroke.
In general, the narrow hooked blades are somewhat flatter than Hartsthal blades, which can make it difficult when mowing on uneven ground with many obstacles. If it feel too flat and the tip tends to dig into the ground when mowing, you can curve the scythe blade by placing it over the edge of your peening stump and gently bending it down with your hands at each end of the blade, applying a bit more force towards the tip. For the very tip (the last 1-2 cm), you can insert it into a crack and bend it.
If you're looking to invest in more than one blade, the standard combination is a Hartsthal 65 and a hooked 75 cm blade! It is best to have a slightly smaller earth angle for Hartsthal so it rides over rocks, protecting the blade.
50cm - Absolutely the best child scythe. Completely superb. Also works for adults, especially if you're short and not very strong. The lighter your equipment are the easier it is to handle the scythe. Surprisingly, you can cut a lot of grass even with a 50cm blade.
65cm - A narrow hooked 65cm blade is the best for beginners who are not yet accustomed to handling a hammer. Both light and easy to peen.
75cm - My personal favorite blade and the one we work with the most in our team. A bit too long, a bit too flat, and a bit too narrow when in terrain with many obstacles and stones. But usually, you're not in such terrain, it's a bit like compromising with having narrow tires on a bicycle. If you drive 95% on asphalt, you have to put up with it not being 100% comfortable on a gravel road. Then you can always switch to a Hartsthal 65 or 60 blade for trickier environments.
85cm - Great for those who are experienced, strong, and enduring in environments that are flat and fairly easy to mow with sparse grass. You can cut very deep with them with a little effort. For example, in sparse marshes with not many obstacles, we bring out the 85cm blades.