The USA-made TITAN PROLOC 1 Barbell Collars attach firmly to any bar with a 47.5mm–50.9mm sleeve, compatible with Olympic and powerlifting bars as well as most logs, cambered bars, Swiss bars, and safety squat bars. Crafted from high-strength nylon to survive the hardest commercial environments for years, the easy on/off knobs work as smoothly as a spring clip but lock down with a far more secure grip.