diff --git a/pcdet/ops/pointnet2/pointnet2_stack/src/ball_query_gpu.h b/pcdet/ops/pointnet2/pointnet2_stack/src/ball_query_gpu.h
new file mode 100644
index 0000000..c74f120
--- /dev/null
+++ b/pcdet/ops/pointnet2/pointnet2_stack/src/ball_query_gpu.h
@@ -0,0 +1,25 @@
+/*
+Stacked-batch-data version of ball query, modified from the original implementation of official PointNet++ codes.
+Written by Shaoshuai Shi
+All Rights Reserved 2019-2020.
+*/
+
+
+#ifndef _STACK_BALL_QUERY_GPU_H
+#define _STACK_BALL_QUERY_GPU_H
+
+#include <torch/serialize/tensor.h>
+#include <vector>
+#include <cuda.h>
+#include <cuda_runtime_api.h>
+
+int ball_query_wrapper_stack(int B, int M, float radius, int nsample,
+    at::Tensor new_xyz_tensor, at::Tensor new_xyz_batch_cnt_tensor,
+    at::Tensor xyz_tensor, at::Tensor xyz_batch_cnt_tensor, at::Tensor idx_tensor);
+
+
+void ball_query_kernel_launcher_stack(int B, int M, float radius, int nsample,
+    const float *new_xyz, const int *new_xyz_batch_cnt, const float *xyz, const int *xyz_batch_cnt, int *idx);
+
+
+#endif