diff --git a/src/core/utils/stream/band.rs b/src/core/utils/stream/band.rs
new file mode 100644
index 00000000..76f2a85a
--- /dev/null
+++ b/src/core/utils/stream/band.rs
@@ -0,0 +1,26 @@
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+/// Stream concurrency factor; this is a live value.
+static WIDTH: AtomicUsize = AtomicUsize::new(32);
+
+/// Practicable limits on the stream width
+pub const WIDTH_LIMIT: (usize, usize) = (1, 1024);
+
+/// Sets the live concurrency factor. The first return value is the previous
+/// width which was replaced. The second return value is the value which was set
+/// after any applied limits.
+pub fn set_width(width: usize) -> (usize, usize) {
+	let width = width.clamp(WIDTH_LIMIT.0, WIDTH_LIMIT.1);
+	(WIDTH.swap(width, Ordering::Relaxed), width)
+}
+
+/// Used by stream operations where the concurrency factor hasn't been manually
+/// supplied by the caller (most uses). Instead we provide a default value which
+/// is adjusted at startup for the specific system and also dynamically.
+#[inline]
+pub fn automatic_width() -> usize {
+	let width = WIDTH.load(Ordering::Relaxed);
+	debug_assert!(width >= WIDTH_LIMIT.0, "WIDTH should not be zero");
+	debug_assert!(width <= WIDTH_LIMIT.1, "WIDTH is probably too large");
+	width
+}
diff --git a/src/core/utils/stream/mod.rs b/src/core/utils/stream/mod.rs
index 4456784f..a5ef17c5 100644
--- a/src/core/utils/stream/mod.rs
+++ b/src/core/utils/stream/mod.rs
@@ -1,3 +1,4 @@
+mod band;
 mod broadband;
 mod cloned;
 mod expect;
@@ -9,6 +10,7 @@ mod try_broadband;
 mod try_ready;
 mod wideband;
 
+pub use band::{automatic_width, set_width, WIDTH_LIMIT};
 pub use broadband::BroadbandExt;
 pub use cloned::Cloned;
 pub use expect::TryExpect;
@@ -19,32 +21,3 @@ pub use tools::Tools;
 pub use try_broadband::TryBroadbandExt;
 pub use try_ready::TryReadyExt;
 pub use wideband::WidebandExt;
-
-/// Stream concurrency factor; this is a live value.
-static WIDTH: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(32);
-
-/// Practicable limits on the stream width
-pub const WIDTH_LIMIT: (usize, usize) = (1, 1024);
-
-/// Sets the live concurrency factor. The first return value is the previous
-/// width which was replaced. The second return value is the value which was set
-/// after any applied limits.
-pub fn set_width(width: usize) -> (usize, usize) {
-	use std::sync::atomic::Ordering;
-
-	let width = width.clamp(WIDTH_LIMIT.0, WIDTH_LIMIT.1);
-	(WIDTH.swap(width, Ordering::Relaxed), width)
-}
-
-/// Used by stream operations where the concurrency factor hasn't been manually
-/// supplied by the caller (most uses). Instead we provide a default value which
-/// is adjusted at startup for the specific system and also dynamically.
-#[inline]
-pub fn automatic_width() -> usize {
-	use std::sync::atomic::Ordering;
-
-	let width = WIDTH.load(Ordering::Relaxed);
-	debug_assert!(width >= WIDTH_LIMIT.0, "WIDTH should not be zero");
-	debug_assert!(width <= WIDTH_LIMIT.1, "WIDTH is probably too large");
-	width
-}