D means that the product is rated in its category in terms of energy efficiency. The Energy Labeling system is based on EU Regulation 2017/1369/EU. D Whirlpool TDLR 6231L FR/N, Top-load, 13.2 lbs (6 kg), B, 76 dB, 1200 RPM, D Whirlpool TDLR 6231L FR/N. Loading type: Top-load. Drum capacity: 13.2 lbs (6 kg), Spin-drying class: B, Noise level (spin): 76 dB, Maximum spin speed: 1200 RPM. Product color: White. Width: 15.7" (400 mm), Depth: 23.6" (600 mm), Height: 35.4" (900 mm). Energy efficiency class: D