Jass Performance soft top guide cap helps locate the soft top when closing and can also eliminate rattles. If yours are cracked you should replace both.
Unlike the genuine Mazda rubber guide caps, these are made from superior material with added carbon fibre for rigidity and graphite to reduce friction (and of course prolong their life).
This is the one with the more flat nose was used in the latter latches, used in NB8Cs after 2003 (until 2005).
NOT the one with the more pointy end was used for all latches until roughly 2003.
Of course the latch/catch combination can be replaced in all cars and it is mandatory to check yours before placing an order.
They are sold as single replacement per side, as they are not always needed for both sides.