The Enduro Bearings 61900 LLU/LLB - ABEC 5 is a top-quality radial bearing designed specifically for bicycles. It features 52100 High-Carbon Chromium alloy races paired with grade 5 Balls with 90% fill, high-pressure, water-proof grease. The LLU/LLB seal combination on these bearings is specially designed to protect against water and dirt contamination. The more protective LLU seal faces outward, towards the elements, while the lighter-contact LLB seals face inward to keep the grease in place. Enduro Bearings offers a range of options for their bearings, including High-Carbon Chromium Steel, 440C Stainless Steel, Ceramic-Hybrid, and XD-15 with Ceramic or Stainless Balls. All of their standard bearings are engineered with deep groove races to accommodate large balls. To provide ultimate protection against the elements, all standard bearings have dual-lip seals that ride in a micro groove, creating a full labyrinth. The Enduro Bearings 61900 LLU/LLB - ABEC 5 is specifically designed for bottom brackets. It has dimensions of 10mm x 22mm x 6mm and meets ABEC 5 grade standards. The grease used is Kyodo Yushi PS-2.