They are replacement blades the Tamiya Modeler’s Knife Pro (item 74098).
• Narrow Chisel blades x5
• 0.55 mm dense.
• Narrower set alongside the available these days chisel blade (Item 74101, Width: 4mm), and hence may be used in tighter areas.
• ideal for eliminating protrusion from flat regions of ribs and molds and so on.