YOPIN Sound Absorbing Material 200kg/m³ High Density Sound Absorption Board Soundproofing Measures Interior Decoration Musical Instruments Soundproofing Noise Reduction 30cm x 30cm Easy DIY Flame Retardant Moisture Proof Insulation Acoustic Panel 30 sheets 6000 yen (60 sheets 11000 yen, 90 sheets 16000 yen) Please let me know the quantity change in the comments. Used item. No pets, no smoking. Used in an office for about a year, from last September. There are no noticeable stains or damage (except for one sheet). It was attached to a soundproof sheet with double-sided tape, so there is no adhesive residue. The included nails are not included.