These are the PREsale prices. 1day can also be bought from drivers for 8€ (children 4€, there is NO regular child fare!-in fact on none of BE's local transport). PREsale is also (should be) possible from all staffed NMBS-stations in Vlaanderen. Machines (sadly quite often broke) are also on most main (BUS)stations, take notes+coins, forgotten if they also do take cards.
deLIJN also runs into NL with various routes (Maastricht-3, Tilburg, Reusel, Hulst (2) and on the combined line Brugge-Breskens (with Connexxion/NL) it is valid untill Sluis/NL on both partners. Some deL cards also taken on the Belgian part of the DKbus dePanne-Duinkerken (Dunkerque), dk if this also applies to Daypasses. Note that 3/5 days are only consecutive. 1 day lasts till 4.00 next morning (to allow the use of nightbuses-though there seem to be fewer and fewer of these).
For smaller use-and if coming back to BE for more- there is also a deLIJNkaart for 16€, which gives 10 rides, with any changes till 60 minutes after first-you can still then do the whole line after the 60 mins expire. In theory the whole of the coastal tram could be done thus-except that very often you have to change anyway at Ostende. It lasts ''forever'' (that means till MoBiB also hits deL), but prices will go up on 1/2 and thus also the amount taken from the card.
On TEC (the wallon counterpart) they favour the MoBiB chipcard and loaded on it is cheaper. 1 day is 8 (10 on bus) or just 4 for 1 of the cities where they run citybuses. However, never mentioned anywhere is that the Charleroi (''Brussels South friendly RYANairport'') has its own sky high special airport fare and non of the normal tix is valid. TEC also has routes into Nl (again Maastricht!), FR and LUX, those into DE (Aachen) however, count as german and its fares from border.