Those are rare and usually come with a 30x wagering condition and a maximum cash-out limit. It is also worth paying attention to the payouts or the so-called Return to Player (RTP).
http://www.lada-xray.net/showthread.php?p=255561#post255561
https://catrachosporelmundo.com/index.php?topic=16747.new#new
https://sample-a11.jumgoo.com/forum.php?mod=viewthread&tid=847&extra=
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http://horsecity.ru/phpBB3/viewtopic.php?f=7&t=455710
http://forexam.ru/component/kunena/?func=view&catid=5&id=172717#172717
https://muchroom.ng/index.php?topic=66036.new#new