With Sakae Ringyo, it seems the name on the arm designates how the arm was made and may be found with different bolt-circle diameters; e.g. "Custom" and "Signature" arms are melt-forged and tumble-polished, and can have 86mm, 110mm, or 118mm BCDs. "Apex" arms are cold-forged, polished, and anodized, and can be found with 86mm or 118mm BCD. "Royal" arms are also cold-forged, polished, and anodized, but AFAIK only came in 144mm BCD. There could even be other variants I haven't encountered or can't recall.