Gel ink refill for Pilot G2 pens, and variations. BLSG205: 0.5mm ball writes a 0.32mm line. BLSG207: 0.7mm ball writes a 0.39mm line. BLSG210: 1.0mm ball writes a 0.48mm line. Not all colours are available in all tip sizes - the more unusual colours are only in the 0.7mm tip. 110mm long, 6mm diameter. Suitable for many pens using 'euro-format' refills, but the 1mm length difference compared to most can make a difference to some pens.