"Professional Gear Sigma" seems to be the successor pen to the "Professional Gear". In some markets these pens are marketed as "Professional Gear II". There are some differences in the clip design and the sizes. Additionally, there is now a bicolor nib also in the "slim" version - and, not to forget, some quite larger differences in the price. Uphill, off course. Soon here: a comparison between a Professional Gear21 and the corresponding Sigma. " Professional Gear " XXXmm YYg *Professional Gear Slim Mini 124mm 16.8g *Professional Gear Slim Silver: red, black, blueberry, white (14K, rhodium-plated, middle size) *Professional Gear Slim Gold: black (14K, 24K gold-plated, middle size) 124mm 17.0g *Professional Gear Slim Saibinagi: red (14K, rhodium-plated, middle size) 129mm 21.6g *Professional Gear Silver: black (21K, bicolor, large size) *Professional Gear Gold: black (21K, bicolor, large size) *Professional Gear Impe...