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

# Flux.2 Klein 4B

> Fastest image generation with Flux.2 Klein 4B

Generate images using the smallest and fastest Flux.2 Klein 4B model.

## Model

```
black-forest-labs/flux.2-klein-4b
```

## Parameters

| Parameter      | Type      | Required | Default  | Description                                                       |
| -------------- | --------- | -------- | -------- | ----------------------------------------------------------------- |
| `prompt`       | string    | Yes      | -        | Text description of the image                                     |
| `aspect_ratio` | string    | No       | `"16:9"` | `"21:9"`, `"16:9"`, `"4:3"`, `"1:1"`, `"3:4"`, `"9:16"`, `"9:21"` |
| `resolution`   | string    | No       | `"1mp"`  | `"0.6mp"`, `"1mp"`, `"2mp"`, `"4mp"`                              |
| `image_urls`   | string\[] | No       | `null`   | Reference image URLs                                              |
| `seed`         | integer   | No       | random   | Seed for reproducibility                                          |

<Note>Klein models do not support `guidance`, `steps`, or `prompt_upsampling`.</Note>

## Example Request

```bash theme={null}
curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "black-forest-labs/flux.2-klein-4b",
    "input": {
      "prompt": "A simple icon of a coffee cup",
      "aspect_ratio": "1:1"
    }
  }'
```

## Response

```json theme={null}
{
  "code": 200,
  "success": true,
  "data": {
    "task_id": "abc123def456",
    "status": "processing"
  }
}
```