Jeroen proudly endorses Warwick basses and plays Warwick Thumb NT series exclusively since 1993. He has played several Thumb NT6 and NT7 basses, each marking different chapters of his musical career. During Pestilence's Spheres era he started playing a Thumb NT6 bass. From 2005 and later on recording Obscura's Cosmogenesis and Omnivium albums he played exclusively fretless Thumb NT6 basses. Since 2011 Jeroen plays fretless Thumb NT7 basses, master-built by Warwick’s custom shop in Germany.