It refers to a percentage of your wagers which you'll get back. Some sites only offer 10 free spins, while others give away a few hundred spins to play certain slots.
http://www.pravoslit.ru/forum/tserkovnaya-...nett-asker.html
http://forum.bandingklub.cz/viewtopic.php?f=41&t=1266086
http://forum3.bandingklub.cz/viewtopic.php...0&t=1467144
https://forum.zweb-apps.xyz/viewtopic.php?t=3480
https://debate.socialism.nl/forum/showthread.php?tid=184584
https://debate.socialism.nl/forum/showthread.php?tid=153484
https://debate.socialism.nl/forum/showthread.php?tid=109867
http://178.210.82.182/forum/learning/44835...er-online-j-t-k
http://www.prepody.ru/topic86635.html
https://mmomakemoneyonline.net/threads/hvor...-online.442601/
http://forum.bandingklub.cz/viewtopic.php?f=38&t=1467335
https://www.ww2.site/forum/viewtopic.php?t=32417
https://debate.socialism.nl/forum/showthread.php?tid=112256
http://pravoslit.ru/forum/leeteratura-xix-...casino-f-t.html
https://mmomakemoneyonline.net/threads/mobi...-casino.356427/
http://www.ria-center.ru/forum/viewtopic.p...=11&t=39980
http://www.prepody.ru/topic95272.html
http://forums.shlock.co.uk/viewtopic.php?f=2&t=426970
http://forum3.bandingklub.cz/viewtopic.php...5&t=1298060
http://forum.bandingklub.cz/viewtopic.php?f=37&t=1218447
https://45.83.123.20/viewtopic.php?t=14747