Tobisho A's, SR-1's & Niwaki GR Pro's
The A Type are an older design and are made with a particularly old technique - the blade (blue paper steel) is brazed to the body (you see the gold ‘glue’). The technique is more time consuming, and uses higher quality material so, are more expensive.
B Type secateurs (such as Niwaki GR Pro, on our site) have more rounded, symmetrically shaped handles.
The Tobisho SR-1 is considered a hybrid of A and B Type. I’ve taken a photo of all three together so you can see the differences.
In real terms, the different is the ‘feel’ in your hand. The Tobisho A-type are a bit more substantial, but they are not necessarily stronger because blue paper steel is very hard and slightly more brittle.
People do love them though. My brother, also a gardener, and a fellow with medium-to-large sized hands, just got to try out the A-types for the first time and he preferred them to the SR-1s. I personally prefer the SR-1s as I find they fit my slightly smaller hand better.