No. That is regular Dwarf Sag. Look for Sagittaria subulata 'True'. That Dwarf Sag in the link would still work. They have the same hardiness. Put a couple root tabs under them, and keeping dosing a little bit of ferts, and you're good to go.
I asked the seller if this is the plant with thin leaves and he said yes. if its not then dont know why he said that.
i googled true dwarf sag but i dont see anything difference between them do you have any pictures of the difference?
thanks