---
description: Explore Ultralytics YOLO neural network modules, Proto to BottleneckCSP. Detailed explanation of each module with easy-to-follow code examples.
keywords: YOLO, Ultralytics, neural network, nn.modules.block, Proto, HGBlock, SPPF, C2, C3, RepC3, C3Ghost, Bottleneck, BottleneckCSP
---

# Reference for `ultralytics/nn/modules/block.py`

!!! Note

    This file is available at [https://github.com/ultralytics/ultralytics/blob/main/ultralytics/nn/modules/block.py](https://github.com/ultralytics/ultralytics/blob/main/ultralytics/nn/modules/block.py). If you spot a problem please help fix it by [contributing](https://docs.ultralytics.com/help/contributing/) a [Pull Request](https://github.com/ultralytics/ultralytics/edit/main/ultralytics/nn/modules/block.py) 🛠️. Thank you 🙏!

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## ::: ultralytics.nn.modules.block.DFL

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## ::: ultralytics.nn.modules.block.Proto

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## ::: ultralytics.nn.modules.block.HGStem

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## ::: ultralytics.nn.modules.block.HGBlock

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## ::: ultralytics.nn.modules.block.SPP

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## ::: ultralytics.nn.modules.block.SPPF

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## ::: ultralytics.nn.modules.block.C1

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## ::: ultralytics.nn.modules.block.C2

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## ::: ultralytics.nn.modules.block.C2f

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## ::: ultralytics.nn.modules.block.C3

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## ::: ultralytics.nn.modules.block.C3x

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## ::: ultralytics.nn.modules.block.RepC3

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## ::: ultralytics.nn.modules.block.C3TR

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## ::: ultralytics.nn.modules.block.C3Ghost

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## ::: ultralytics.nn.modules.block.GhostBottleneck

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## ::: ultralytics.nn.modules.block.Bottleneck

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## ::: ultralytics.nn.modules.block.BottleneckCSP

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## ::: ultralytics.nn.modules.block.ResNetBlock

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## ::: ultralytics.nn.modules.block.ResNetLayer

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## ::: ultralytics.nn.modules.block.MaxSigmoidAttnBlock

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## ::: ultralytics.nn.modules.block.C2fAttn

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## ::: ultralytics.nn.modules.block.ImagePoolingAttn

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## ::: ultralytics.nn.modules.block.ContrastiveHead

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## ::: ultralytics.nn.modules.block.BNContrastiveHead

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## ::: ultralytics.nn.modules.block.RepBottleneck

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## ::: ultralytics.nn.modules.block.RepCSP

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## ::: ultralytics.nn.modules.block.RepNCSPELAN4

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## ::: ultralytics.nn.modules.block.ADown

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## ::: ultralytics.nn.modules.block.SPPELAN

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## ::: ultralytics.nn.modules.block.Silence

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## ::: ultralytics.nn.modules.block.CBLinear

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## ::: ultralytics.nn.modules.block.CBFuse

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