Abstract: An American style football includes a prolate spheroidal shaped outer surface having a first nose and a second nose opposite the first nose, the first nose and the second nose located along a longitudinal axis of the football. The football has a weight of at least 390 g and no greater than 410 g, a longitudinal circumference of at least 660 mm and no greater than 673 mm, a short circumference of at least 486 mm and no greater than 495 mm and a length of at least 267 mm and no greater than 279 mm.

Abstract: A flag system includes a flag carrier and a flag unit. The flag unit includes a flag, and a flag coupler connected to the flag and configured to be releasably connected to the flag carrier. The flag unit is user reconfigurable between a first flag unit separation difficulty state and a second flag unit separation difficulty state.

Abstract: A game ball for an optical tracking system includes a tracked region on the game ball. The tracked region includes a retro reflective surface and an optical filter overlying the retro reflective surface.

Abstract: A variable loby game ball has an outer surface that includes a first pole, a second pole opposite the first pole and outer lobes. The outer lobes extend between the first pole and the second pole. Recessed channels that vary in at least one of width, depth and cross-sectional shape extend along consecutive lobes.

Abstract: A portable power tool includes a housing, a motor enclosed within the housing, an accessory tool holder secured to the output shaft of the motor, and an attachment interface on a nose portion near the accessory tool holder. An attachment is configured to attached and removed from the nose portion of the housing. The attachment includes a housing interface that is configured to interact with the attachment interface to position the attachment at a predetermined position on the nose portion of the housing. The attachment interface and the housing interface are configured to be magnetically attracted to each other with sufficient force to retain the attachment on the nose portion of the housing during normal operating conditions while allowing the attachment to be removed from the nose portion of the housing by hand by the operator.

Abstract: A portable power tool includes a housing, a motor enclosed within the housing, an accessory tool holder secured to the output shaft of the motor, and an attachment interface on a nose portion near the accessory tool holder. An attachment is configured to attached and removed from the nose portion of the housing. The attachment includes a housing interface that is configured to interact with the attachment interface to position the attachment at a predetermined position on the nose portion of the housing. The attachment interface and the housing interface are configured to be magnetically attracted to each other with sufficient force to retain the attachment on the nose portion of the housing during normal operating conditions while allowing the attachment to be removed from the nose portion of the housing by hand by the operator.