These are two trays designed to fit larger fountain pens: one to fit longer pens like Twsbi Eco, Twsbi Go, and Pilot Kakuno (as pictured) and one to fit shorter pens like Kaweco Sport (as pictured). 

The larger tray measures 110mm x 150mm and can hold 5 pens with about a 17mm diameter each. The smaller tray is 40mm x 110mm and can hold 2 pens with about a 15mm diameter each. 

It is meant to fit in the top trays of the Cantilever tool/sewing box designed by @kluwdr_2535102 (link below).