Sleeping Bag

Restores a little HP to party. Also saves game. Used outdoors.
Price 75 gil (50 gil on Easy)
Value 37 gil (25 gil on Easy)
Sold In Pravoca, Cornelia
Restores 30 HP to all party members, and allows the player to save the game. Can only be used outdoors.

The Sleeping Bag is only available in the first two towns, but it is useful throughout the game as a relatively cheap way to save when you don't need a lot of healing (or just don't want to use a more expensive alternative).
Compare Sleeping Bag to other Items
Shops: Where Sleeping Bag is sold – 2 shown
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 Map Shop
Cornelia Items
Pravoca Items
Treasures: Containing Sleeping Bag – 2 shown
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 Map
The specifics of where this treasure can be found
Notes
Terra Cavern B3 Found in a chest in the southeastern room
Ice Cavern B1 Found in a chest in the central room
Gold Needle Tent

Related

TENT

Price 75 G
Sold In Pravoka, Coneria
Restores 30 HP to all party members and allows the player to save the game. Can only be used outdoors.

The TENT is only available in the first two towns, but it is useful throughout the game as the cheapest way to save. The healing power of the TENT is equivalent to four HEAL Potions (one given to each party member), making it cost-effective for healing on the World Map.

Sleeping Bag

Recovers HP/MP to 100%
Price 500 GP
Value 250 GP
Statuses Dark, Zombie, Poison, Imp, Petrify, Clear
World of Balance Shops Figaro Castle, Kohlingen, Mobliz, Narshe, Nikeah, Phantom Train (v2, v3), Returners' Hideout, South Figaro
World of Ruin Shops Albrook, Jidoor, Kohlingen, Nikeah, Thamasa, Tzen
Sleeping Bags have the same effect as Tents, but for only a single character at a time. (They also don't cure Wound because they cannot be used on a Wounded character.) If you only have one or two characters, or if your other characters don't need restoration, Sleeping Bags can be fairly cost-effective. A good tactic early in the game before you obtain any Espers is to have Terra or Celes use Cure to heal up the party, then use a Sleeping Bag on just them to restore their MP on the cheap.