The one on the stbd side is a reaching strut. It's used with a symetrical spinnaker when sailing with the pole all the way forward. In that position, the pole guy/windward spinnaker sheet will be against the upper shroud
and can saw itself in half in short order. The reaching strut attaches to the side of the mast
with the spinnaker pole like end and the other end (the one pictured with the roller and stub finger) pushes the pole guy/windward spinnaker sheet off the upper shroud
. You will need to add some lines that attach to the lower shrouds to stabilize the reaching strut in position.
Collapsible poles are not for spinnakers as they can't take the compression
loads that occur with a spinnaker. They don't even do well with large genoas if used on a boat that is at the upper end of the size chart. The collapsible pole on my boat pretzeled after 2 days poling out my 130% genoa
on the way to Hawaii
. The boat is at the upper end of the size reccomendations for the ppole diameter/length but my boat has a relatively small 'J' measurement for its length. It worked fine in sailing around the Bay but couldn't hack it in moderately strong winds. Of course it had to bend at 0400 on a moonless, overcast night. Fortunately, also have a spinnaker pole which allowed me to continue wing on wing for the final 8 days of the passage