The HARD TO BUFF OTR 970 REFILL features 120ml of highly pigmented, ultra permanent alcohol based black ink.
This superior ink is extremely UV resistant and is resistant to both scratching and heat. The OTR.970 is designed to refill the Hard To Buff marker series, but will also work perfectly in your favorite alcohol-based ink markers, Pump action valve markers, brushes, air brushes, or any mop or squeeze marker.