A sliotar (or sliothar - may derive from Irish sliabh, meaning "mountain" and thar meaning "across") is a hard solid sphere slightly larger than a tennis ball, consisting of a cork core covered by two pieces of leather stitched together. Sometimes called a 'puck' or 'hurling ball', it resembles an American baseball with more pronounced stitching. It is used in the Gaelic sports of hurling and camogie.

Early (pre-GAA) sliotars used various materials, depending on the part of the country:

• bronze
• wood and leather
• wood, rope and animal hair

Johnny McAuliffe is the Irishman who is credited with the modern design. Born in Tullybrackey, Bruff, Co. Limerick in 1896 he was both a hurler and a mender of some note.

Before his improvements the ball had the following general characteristics:

• Non-uniform: Poor manufacturing produced inconsistent shapes
• Heavier: Minimum weight of 7 ounces (200 grams) as prescribed by GAA rules
• Cumbersome: Large horse-hair packed ball tended to lose shape during play
• Non water-resistant: Ball tended to become soggy during wet play
• Low-visibility: Brown ball tended to "get lost" against Cusack stand (constructed in 1937)

McAuliffe made the following changes:

• High-standard: Cork core, 2 piece pigskin with lip stitching
• Sure-flight: Maintains shape over course of game leading to safer play
• High-visibility: Hard-wearing white tanned pigskin impervious to grass stains
• Lighter: Weight of approximately 3.5 ounces (100 grams) - about half the original
• Water-resistant: Does not become heavy in wet weather leading to consistent handling

Given these changes, faster playing surfaces and fitter players hurling was transformed into the modern high-scoring game loved today.