This is the Gundam Real Touch Gray #3 Paint Marker by Mr. Hobby.
Mr. Hobby® Gundam Real Touch Marker GM406 GREY 3 DARK GRAY
Markers
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Mr. Hobby Paint - A-Z Toy Hobby – Tagged type-Marker
Mr. Hobby® Gundam Real Touch Marker GM406 GREY 3 DARK GRAY
Gundam Marker #GM406 - Real Touch Gray 3 by GSI Creos
Mr. Hobby Gundam Marker: Real Touch Marker Gray 3 (GM406)
GUNZE – Page 15 – Trainz
Mr. Hobby Gundam Marker: Real Touch Marker Gray 3 (GM406)
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Mr. HOBBY — GUNPLA SA
Five color markers including Grey-1, Grey-2, Blue-1, Red-1, and Orange-1, with a colorless blender make the set of six 6 brush type markers for
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Gundam Marker #GM406 - Real Touch Gray 3 by GSI Creos