Back in the days of 35mm film, a 50mm prime was considered a 'standard' lens. That's because it gives pretty much the same perspective as viewing a scene with the human eye, without the magnification of a telephoto lens or the shrinkage a wide-angle lens uses to squeeze more into the frame.
The flexi disc (also known as a phonosheet or Soundsheet, a trademark) is a phonograph record made of a thin, flexible vinyl sheet with a molded-in spiral stylus groove, and is designed to be playable on a normal phonograph turntable.
The Core Stability Disk is an excellent way to add a new level of difficulty to your workout. The soft disk can be utilized in pilates, yoga or regular workouts to work your core muscles, increase balance and stability. Difficulty may be increased by adding air or decreased by releasing air.