> ## Documentation Index
> Fetch the complete documentation index at: https://docs.comfy.org/llms.txt
> Use this file to discover all available pages before exploring further.

# SetFirstSigma - ComfyUI Built-in Node Documentation

> Complete documentation for the SetFirstSigma node in ComfyUI. Learn its inputs, outputs, parameters and usage.

> This documentation was AI-generated. If you find any errors or have suggestions for improvement, please feel free to contribute! [Edit on GitHub](https://github.com/Comfy-Org/embedded-docs/blob/main/comfyui_embedded_docs/docs/SetFirstSigma/en.md)

The SetFirstSigma node modifies a sequence of sigma values by replacing the first sigma value in the sequence with a custom value. It takes an existing sigma sequence and a new sigma value as inputs, then returns a new sigma sequence where only the first element has been changed while keeping all other sigma values unchanged.

## Inputs

| Parameter | Data Type | Required | Range          | Description                                                                      |
| --------- | --------- | -------- | -------------- | -------------------------------------------------------------------------------- |
| `sigmas`  | SIGMAS    | Yes      | -              | The input sequence of sigma values to be modified                                |
| `sigma`   | FLOAT     | Yes      | 0.0 to 20000.0 | The new sigma value to set as the first element in the sequence (default: 136.0) |

## Outputs

| Output Name | Data Type | Description                                                                           |
| ----------- | --------- | ------------------------------------------------------------------------------------- |
| `sigmas`    | SIGMAS    | The modified sigma sequence with the first element replaced by the custom sigma value |