I saw these at a music concert I attended recently. What are these large black rectangular tabs filled with water for that was placed on the ground around the speaker poles? :
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Metal, Steel, Thailand, Speaker, Concert. Stadium Speakers Rack Over A Blue Sky. Live Music Background. Stock Photo, Picture And Royalty Free Image. Image 129207728.
Concert Club V Series - Features - Speakers - Professional Audio - Products - Yamaha - Africa / Asia / CIS / Latin America / Middle East / Oceania