Reserva 1214 Travel Round Size 6 has a brush head that measures about 3.6mm Diameter x 19mm Long * Kolinsky-Tajmyr Sable is 100% male Kolinky sable, is sourced from Tajmyr region in northern Siberia, is considered the elite hair for watercolor, points perfectly and has an extraordinary capacity to retain liquids * Escoda brushes boast trademarked tripled crimped ferrule ensuring a lifetime secure fit, unique curing process that locks each hair in place creating a permanent brush shape and all wooden handles are ergonomially designed and made from the finest brich wood available * Escoda"s ISO 9001/100 Cerification ensures that each brush is engineered and hand crafted to exacting standards and is supported by Escoda"s Lifetime Guarantee against workmanship defect if purchased from an authorized dealer * Since fine art brushes are hand crafted, please expect some variation to the listed dimensions