One Private Reserve Schmidt 635 Mini D1 Refills - Blue Medium Tip - Blue Ink - 635 Mini D1 size ball point refill by Schmidt. Stainless steel with 0.7 mm Tungsten Carbide ball. Five 635 refill with Medium writing stroke. D1 refill equipped with stainless steel tip and tungsten carbide ball. Schmidt Refill 635 M with Blue Ink. Refill Reads: Private Reserve Ink 635 Ensure Top Quality - Buy Direct from Lanier Pens - Length: 2.6 inch (66.0mm) Made in Germany by Schmidt - Distributed in the USA by Lanier Pens