All I can say for now is that's not the coin you selected.
Can't say if it's really Gallienus, I would like to tell you which emperor is in your coin, but I'm having trouble to read the upper letters due to the angle of the photo.
But I can say outright it's not the one you linked because in your coin the lettering ends in “…VS AVG”.
Same for the reverse side, in your coin the text is too large to be simply “VIRTVS AVG”, the “VIRTV” begins at 7h and already ends at 10h.
On the flip side, the mintmark is well visible, it's XXI(?) - don't know if there's really a 4th letter.
Thank you very much, I found only 1 and the images are not good. Though it's An Antoninianus of Emperor Tacitus (reigned 275-276 AD) with a "VIRTVS PERPETVA" reverse legend. but mine is not whole I think. On the scale it's 2.78 grams