This adjustable double slot punch cuts 2 slots, 3.8mm long, with the gap of your choice in between.
Gaps can be set at: 5.7mm, 8.4mm, 10.8mm, 14mm, 16.7mm, 20.3mm and 24.75mm.
With the blades set at 8.4mm, this tool is ideal for fitting the small size of magnetic handbag poppers as seen in related items below.