Amazon.com: Rotring 600 3-in-1 Multicolor Pen and Mechanical Pencil, Switches Between 2 Ballpoint Pen Fine Point Tips (Black and Red Ink) and 1 Mechanical Pencil Tip (0.5mm Lead), Black Barrel : Everything Else
Rotring 600 TRIO Pen Black / Made in Germany Knurled Grip / very rare | eBay
My Rotring 600 and Trio Pen from the mid 90s : r/mechanicalpencils
Drafting and Mechanical Pencils: rotring trio pencil - 502705
Rotring 600 3-in-1 2 Color Fine Ballpoint Multi Pen + 0.5 mm Pencil - Silver | JetPens
Vintage Rotring 600 Newton Trio 3 in 1 Combo in Near Mint Condition | eBay
Rotring 600 Series 3 in 1 Multi Pen - Camouflage Green Brass Body – Art&Stationery