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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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