The folding feature is a big safety improvement and can reduce blade damage between uses as it allows the blade to be folded back into the handle.
The wider hand grip is also more comfortable to hold than a conventional blade handle.
Choose the correct size for your blades:
no 3 for blades 10, 11, 12 and 15
no 4 for blades 20, 21, 22, 23 and 24 (shown in photo)