The Fluidigm Helios is a third-generation mass cytometer (CyTOF) that uniquely combines time-of-flight mass spectrometry with metal-tagged antibodies for high-dimensional single-cell analysis. It allows for the simultaneous detection of over 40 (up to 50) protein markers on a per-cell basis, providing unparalleled insight into cellular diversity and function without the need for compensation between channels. The Helios platform offers an expanded mass range of 135 discrete channels with minimal signal overlap or background noise, improved sensitivity for lower abundance targets, and a high throughput of 200-400 events/sec (up to 500 events/sec maximum). It is ideal for generating comprehensive single-cell datasets and can be used for both high-dimensional single-cell suspension analysis and, when coupled with the Hyperion, for tissue imaging. It features an intuitive software interface with real-time data display and normalization.