diff --git a/custom_extensions/nms/src/cuda_helpers.h b/custom_extensions/nms/src/cuda_helpers.h
new file mode 100644
index 0000000..af32f60
--- /dev/null
+++ b/custom_extensions/nms/src/cuda_helpers.h
@@ -0,0 +1,5 @@
+#pragma once
+
+#define CUDA_1D_KERNEL_LOOP(i, n)                                \
+  for (int i = (blockIdx.x * blockDim.x) + threadIdx.x; i < (n); \
+       i += (blockDim.x * gridDim.x))
diff --git a/custom_extensions/roi_align/src/cuda_helpers.h b/custom_extensions/roi_align/src/cuda_helpers.h
new file mode 100644
index 0000000..af32f60
--- /dev/null
+++ b/custom_extensions/roi_align/src/cuda_helpers.h
@@ -0,0 +1,5 @@
+#pragma once
+
+#define CUDA_1D_KERNEL_LOOP(i, n)                                \
+  for (int i = (blockIdx.x * blockDim.x) + threadIdx.x; i < (n); \
+       i += (blockDim.x * gridDim.x))
diff --git a/custom_extensions/sandbox/src/sandbox.h b/custom_extensions/sandbox/src/sandbox.h
new file mode 100644
index 0000000..c67254f
--- /dev/null
+++ b/custom_extensions/sandbox/src/sandbox.h
@@ -0,0 +1,3 @@
+
+
+#define getNBlocks(m,n) ( (m+n-1) / (n) ) // m = nr of total (required) threads, n = nr of threads per block.
\ No newline at end of file