Match issued means that the boots have been custom made for and supplied to the professional player, but have remained unworn and unused - essentially a spare pair. There are a number of reasons a pair of players' boots may not get used, for example in times such as during pre season and at the start of a season where players may not use the SG boots supplied to them by their sponsor as the pitches are not soft enough, so if they'll remain match issued and prepared if unused. Another time this can happen is if a player is supplied a pair during an injury spell, the boots will still be match issued and prepared but may not actually get worn as the next colourway may be released by the time the player is fit to play again.  Match worn means that the boots have been worn by the player in a match or multiple matches. This may also include training sessions, however that will differ from player to player. Some change boots almost every match, so sometimes their pairs may only ever be worn once or twice -