PreSonus ULT18 18-Inch Powered Subwoofer AT2020 The inner rack chassis is

The inner rack chassis is built of high strength/lightweight aluminum alloy extrusions with 11 gauge hot rolled carbon steel rack rails to meet EIA-310 standards

I/O Meter: 6 Independent Six-Segment Lightpipe Output Meters that range from -30 to +20 dBu

and all of the extras that make your studio work easier and more efficient

but with IP 65 rating

PreSonus ULT18 18-Inch Powered Subwoofer AT2020 The inner rack chassis isPreSonus ULT18 18 Inch Powered Subwoofer Designed to complement any full range PA loudspeaker and a perfect companion for the PreSonus ULT12 and ULT15, the ULT18 subwoofer delivers a powerful, clear, and accurate low end punch. With 2,000 watts of Class D power and a direct radiating, ported enclosure, it delivers the detailed low frequency performance audio pros demand. Its custom 18 inch low frequency transducer with 4 inch voice coil provides 7 mm