The sporran was a traditional Human clothing accessory, typically worn by Human males of Scottish descent, while wearing a kilt. It is in the form of a pouch or purse, and affixed to a chain around the wearer's waist. It is generally worn in front of the kilt, and often has two or three tassels in front of it, and can be used to keep things in.
When engineer Montgomery Scott entered the drinking competition with Tomar, one of the Kelvans in Human form, a number of Scottish objects could be seen hanging on his room's wall, such as a kilt, sporran, targe and also bagpipes. (TOS: "By Any Other Name") Scott was also allowed to wear a sporran as part of his dress Starfleet uniform, to reflect his heritage. (TOS: "Is There in Truth No Beauty?", "The Savage Curtain")