These Lock-Jaw collars are designed to fit Olympic Style bars, 2 inches in diameter. They are safe for barbells and dumbbells (up to 200lb vertical capacity per collar!). The Lock-Jaw collar features a thick nylon frame and fully-captured pressure pads, making it the most durable resin collar available. The quick-action lever securely clamps the collar once positioned on the bar. Lock-Jaw collars will withstand the toughest environment. Innovative design, superior durability, and exceptional performance make the Lock-Jaw collar an excellent choice for any Olympic style bar