The Premier Ball (プレミアボール Premier Ball) was created for a special event. It is entirely white except for the band around the middle which is red. According to the official Pokémon Colosseum game guide, it has the same catch rate as a regular Poké Ball, Catch rate = 1 * (((( 4 * Max HP - 2 * HP ) * Catch Rate ) / Max HP ) + Status + 1 ) / 256.
But "it looks cooler." It can be obtained by purchasing 10 regular Poké Balls from a shop (Generation III onward). On your birthday the Premier Ball acts like a Master Ball with a 100% catch rate.