50 1/4" Silicon Nitride Ceramic Si3N4 Bearing Balls Description Super precision Grade 5 silicon nitride balls reduce friction by approximately 10% over steel balls and require less lubricant, reducing losses from lubricant drag. These ceramic bearings are stiffer than steel bearings balls and weigh less. Features: Package length :0.3 cm Package width :5.1 cm Package height :7.6 cm Made in China Product Details: Brand: Moore Bike Balls Material: Silicon Nitride ceramic Bearing Type: Ball Bearing Package Dimensions ‏ : ‎ 2.99 x 2.01 x 0.12 inches; 0.18 Ounces Item model number ‏ : ‎ Si3N4 1/4 050 Date First Available ‏ : ‎ July 8, 2014 Manufacturer ‏ : ‎ BC Precision Best Sellers Rank: #670,456 in Industrial & Scientific (See Top 100 in Industrial & Scientific) #7,521 in Deep-Groove Ball Bearings #7,521 in Deep-Groove Ball Bearings Customer Reviews: 5.0 5.0 out of 5 stars 2 ratings