I think its the one with velcro straps...like my Bontrager one. I struggled to figure out how it was mounted
Fasten the front strap round the seatpost first.
Take each velcro strap (thats mounted at the top of the bag)..pass it round the same side of the saddle rail(behind the seat clamp), pull it down , pass it through the 'buckle' on the bottom of the bag, then back up and it velcros itself on the strap before the 'buckle'
Repeat the other side.
It looks the same system as mine....worth a try.