Centrifuge Rotors come in a wide variety of sizes, configurations, materials, and weights to best suit an application and instrument type. Each manufacturer has a library of both fixed-angle rotors and swing bucket rotors, each for use with specific machines for applications in microbiology, tissue culture, molecular biology and genomics, drug discovery and proteomics, life sciences, and clinical applications. Fixed Angle rotors hold tubes at an angle and are useful for pelleting bacteria and cells, isopycnic separation of macromolecules. Swing out Rotors often can be configured to hold not only differently sized tubes but also TaqMan cards, PCR plates and other lab vessels for a flexible option. These centrifuge rotors also swing out to a horizontal angle letting samples resolve in gradients of density and are quite effective for separation solutions. Rotors are available from manufacturers such as Beckman Coulter, Thermo Scientific, Sorvall, Fisher Scientific, Fiberlite, Hettich, and Eppendorf.