Which Spring Bars are correct?

I changed my Omega Planet Ocean 8900 tonight and swapped the heavy metal bracelet for the OEM Nato strap. But when I took off the bracelet I noticed the spring bars were straight and there were 2 additional spring bars in the box that came with the watch in a plastic bag that were curved. Does anybody know which spring bars I should be using for the watch based on what it shipped with originally? I'm trying to figure out the mystery of where the curved ones came from or if the straight ones are the correct ones to be used.