The Flow Cytometry Absolute Count Standard™ consists of highly uniform cell-sized microspheres labeled with a full spectrum dye, and provided at a known concentration. These beads fluoresce in FL1, FL2, and FL3, allowing them to be used as count standards in all three channels.

A test requires one drop (50μl) of particle suspension, which is equivalent to ~100,000 particles. Bangs Flow Cytometry Standards are 7-9μm in diameter (unless otherwise noted) to approximate the size of human lymphocytes.