Type19 Garmin Cateye Combo Mount (double-sided narrow type, with bottom adapter) for 25.4mm [190-GM+GP-254] and light adapter for CATEYE Type 2 (made of aluminum) for H-34N compatible light [ GP-CATHL2] and Shimano Di2 junction spacer for lower adapter [Di2-EW90-400Spacer]. These three items will allow him to install a Garmin or Cateye cycle computer and his Cateye light + Di2 junction (SM-EW90-A/B) at the same time. Furthermore, since it is a combo model, it comes with a dedicated lower adapter (GP-K400A) with a GoPro interface, allowing you to attach cameras such as the GoProHERO series, Shimano, Garmin, and fly12. *For compatibility with cycle computers and lights, please see the compatible models for combo mounts and various adapters. *There are models that are compatible with multiple models even if the brand is the same.