The Cokin Filter X028 Warm (81C) is a resin filter that adds a warm colour tone to your images. Blue tones become more orange. The filter has a strength of 1/4th stop and lowers the colour temperature from 3600 to 3200 Kelvin. The filter is suitable for use in the Cokin BX-100A filter holder. This 81C has a slightly stronger effect than the 81B version (X027).