JET Rail Linear Ball Bearing Higher loads 3/4" Jet Rail Pillow Block Dynamic Load = 1200 Lbs. Moderate  loads 3/4" Ball Bearing Pillow Block Dynamic Load = 470 lbs.   Sealed for life rollers Balls open to contaminants when seal is torn or by-passed. Repair kit enables you to replace rollers and rebuild bearing block in the field Throw away Rolls over debris and has a scraper option to clear roller pathway Entraps debris and fails, scoring shaft. Balls can fall out.   Low noise, smooth linear motion. Minimal resonant energy passed back to system   Noisy - "zings" down the shaft Transmits vibration into shafting. Poor choice for optics and vibration sensitive equipment Fixed and Adjustable floating blocks for shaft misalignment No adjustments for side-to-side misalignment