The 10,000 btu casement slider air conditioner uses eco-friendly refrigerant, will cool up to 450 sq ft. quiet operation by unit's high efficiency compressor and fan, 3-speed fan control, and full range air direction control.. This casement window air conditioning unit is also ul listed. pros. narrow casement or sliding window with multiple energy modes, follow me remote and eer 10.4 . air conditioner size. the dimensions of this vertical window ac unit are 14