The Sand Rod is an item in A Link Between Worlds. It allows Link to raise pillars of sand, which he can use in his favor. Link can use Ravio's Bracelet to merge into them; he can use them as a bridge, or he can use them to avoid enemies.
The Sand Rod is one of the many items available at Ravio's Shop. However, it is not initially available, as someone else has already rented it from Ravio. Link knows this character to be Osfala, the apprentice of Sahasrahla that was captured by Yuga. Because of this, the Sand Rod is not available until much later in the game.
Once Link has freed Osfala from his painting in the Thieves' Hideout, Osfala gives Link the Sand Rod, asking Link if he can return it to Ravio. However, the moment Link leaves the building, Sheerow swoops in and takes the rod from Link. From that point on, the Sand Rod is available for both rent and purchase at the shop, for 50 and 800 Rupees, respectively.