diff --git a/ion/src/device/usb/Makefile b/ion/src/device/usb/Makefile
index c04812786..6fa7682eb 100644
--- a/ion/src/device/usb/Makefile
+++ b/ion/src/device/usb/Makefile
@@ -9,14 +9,17 @@ usb_objs += $(addprefix ion/src/device/usb/, \
 )
 
 usb_objs += $(addprefix ion/src/device/usb/stack/, \
+  bos_descriptor.o\
   configuration_descriptor.o \
   descriptor.o\
   device_descriptor.o\
+  device_capability_descriptor.o\
   dfu_functional_descriptor.o\
   interface_descriptor.o\
   language_id_string_descriptor.o \
   streamable.o\
   string_descriptor.o\
+  webusb_platform_descriptor.o\
 )
 
 USB_DFU_XIP_FLASH := 0
diff --git a/ion/src/device/usb/stack/bos_descriptor.cpp b/ion/src/device/usb/stack/bos_descriptor.cpp
new file mode 100644
index 000000000..069e6d56e
--- /dev/null
+++ b/ion/src/device/usb/stack/bos_descriptor.cpp
@@ -0,0 +1,22 @@
+#include "bos_descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+void BOSDescriptor::push(Channel * c) const {
+  Descriptor::push(c);
+  c->push(m_wTotalLength);
+  c->push(m_bNumDeviceCaps);
+  for (uint8_t i = 0; i < m_bNumDeviceCaps; i++) {
+    m_deviceCapabilities[i].push(c);
+  }
+}
+
+uint8_t BOSDescriptor::bLength() const {
+  return Descriptor::bLength() + sizeof(uint16_t) + sizeof(uint8_t);
+}
+
+}
+}
+}
diff --git a/ion/src/device/usb/stack/bos_descriptor.h b/ion/src/device/usb/stack/bos_descriptor.h
index b4c2d7244..ce2626099 100644
--- a/ion/src/device/usb/stack/bos_descriptor.h
+++ b/ion/src/device/usb/stack/bos_descriptor.h
@@ -1,21 +1,36 @@
+#ifndef ION_DEVICE_USB_STACK_BOS_DESCRIPTOR_H
+#define ION_DEVICE_USB_STACK_BOS_DESCRIPTOR_H
+
+#include "descriptor.h"
+#include "device_capability_descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
 class BOSDescriptor : public Descriptor {
 public:
-      BOSDescriptor(const CapabilityDescriptor * capabilityDescriptors, int number) :
-      Descriptor(...)
-      m_wTotalLength(somme des size des capDesc),
-      bNumDeviceCaps(number)
-    {
-    }
-  uint16_t copy(void * target) override {
-    super::copy();
-    for (capability in m_deviceCapabilities) {
-      capability->copy(target+machinchose,...);
-    }
+  constexpr BOSDescriptor(
+      uint16_t wTotalLength,
+      uint8_t bNumDeviceCapabilities,
+      const DeviceCapabilityDescriptor * deviceCapabilities) :
+    Descriptor(0x0F),
+    m_wTotalLength(wTotalLength),
+    m_bNumDeviceCaps(bNumDeviceCapabilities),
+    m_deviceCapabilities(deviceCapabilities)
+  {
+  }
+protected:
+  void push(Channel * c) const override;
+  virtual uint8_t bLength() const override;
 private:
-    uint16_t wTotalLength; // Length of this descriptor and all of its sub descriptors
-    uint8_t bNumDeviceCaps; // The number of separate device capability descriptors in the BOS
+  uint16_t m_wTotalLength;
+  uint8_t m_bNumDeviceCaps;
+  const DeviceCapabilityDescriptor * m_deviceCapabilities;
+};
 
-  DeviceCapabilityDescriptor * m_deviceCapabilities;
-} __attribute__((packed));
+}
+}
+}
 
-static_assert(sizeof(DeviceDescriptor) == 12);
+#endif
diff --git a/ion/src/device/usb/stack/device_capability_descriptor.cpp b/ion/src/device/usb/stack/device_capability_descriptor.cpp
new file mode 100644
index 000000000..e3ab162d4
--- /dev/null
+++ b/ion/src/device/usb/stack/device_capability_descriptor.cpp
@@ -0,0 +1,18 @@
+#include "device_capability_descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+void DeviceCapabilityDescriptor::push(Channel * c) const {
+  Descriptor::push(c);
+  c->push(m_bDeviceCapabilityType);
+}
+
+uint8_t DeviceCapabilityDescriptor::bLength() const {
+  return Descriptor::bLength() + sizeof(uint8_t);
+}
+
+}
+}
+}
diff --git a/ion/src/device/usb/stack/device_capability_descriptor.h b/ion/src/device/usb/stack/device_capability_descriptor.h
new file mode 100644
index 000000000..cf600c9f1
--- /dev/null
+++ b/ion/src/device/usb/stack/device_capability_descriptor.h
@@ -0,0 +1,31 @@
+#ifndef ION_DEVICE_USB_STACK_DEVICE_CAPABLITY_DESCRIPTOR_H
+#define ION_DEVICE_USB_STACK_DEVICE_CAPABLITY_DESCRIPTOR_H
+
+#include "descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+class BOSDescriptor;
+
+class DeviceCapabilityDescriptor : public Descriptor {
+  friend class BOSDescriptor;
+public:
+  constexpr DeviceCapabilityDescriptor(uint8_t bDeviceCapabilityType) :
+    Descriptor(0x10),
+    m_bDeviceCapabilityType(bDeviceCapabilityType)
+  {
+  }
+protected:
+  void push(Channel * c) const override;
+  virtual uint8_t bLength() const override;
+private:
+  uint8_t m_bDeviceCapabilityType;
+};
+
+}
+}
+}
+
+#endif
diff --git a/ion/src/device/usb/stack/webusb_platform_descriptor.cpp b/ion/src/device/usb/stack/webusb_platform_descriptor.cpp
new file mode 100644
index 000000000..76994cee1
--- /dev/null
+++ b/ion/src/device/usb/stack/webusb_platform_descriptor.cpp
@@ -0,0 +1,24 @@
+#include "webusb_platform_descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+void WebUSBPlatformDescriptor::push(Channel * c) const {
+  DeviceCapabilityDescriptor::push(c);
+  c->push(m_bReserved);
+  for (int i = 0; i < k_platformCapabilityUUIDSize; i++) {
+    c->push(m_platformCapabilityUUID[i]);
+  }
+  c->push(m_bcdVersion);
+  c->push(m_bVendorCode);
+  c->push(m_iLandingPage);
+}
+
+uint8_t WebUSBPlatformDescriptor::bLength() const {
+  return DeviceCapabilityDescriptor::bLength() + sizeof(uint8_t) + k_platformCapabilityUUIDSize*sizeof(uint8_t) + sizeof(uint16_t) + 2*sizeof(uint8_t);
+}
+
+}
+}
+}
diff --git a/ion/src/device/usb/stack/webusb_platform_descriptor.h b/ion/src/device/usb/stack/webusb_platform_descriptor.h
new file mode 100644
index 000000000..d9764a0b0
--- /dev/null
+++ b/ion/src/device/usb/stack/webusb_platform_descriptor.h
@@ -0,0 +1,41 @@
+#ifndef ION_DEVICE_USB_STACK_WEBUSB_PLATFORM_DESCRIPTOR_H
+#define ION_DEVICE_USB_STACK_WEBUSB_PLATFORM_DESCRIPTOR_H
+
+#include "device_capability_descriptor.h"
+
+namespace Ion {
+namespace USB {
+namespace Device {
+
+class WebUSBPlatformDescriptor : public DeviceCapabilityDescriptor {
+public:
+  constexpr WebUSBPlatformDescriptor(uint8_t bVendorCode, uint8_t iLandingPage) :
+    DeviceCapabilityDescriptor(0x05),
+    m_bReserved(0),
+    m_platformCapabilityUUID{
+      /* Little-endian encoding of {3408b638-09a9-47a0-8bfd-a0768815b665}.
+       * See https://wicg.github.io/webusb/#webusb-platform-capability-descriptor */
+      0x38, 0xB6, 0x08, 0x34, 0xA9, 0x09, 0xA0, 0x47,
+      0x8B, 0xFD, 0xA0, 0x76, 0x88, 0x15, 0xB6, 0x65},
+    m_bcdVersion(0x0100),
+    m_bVendorCode(bVendorCode),
+    m_iLandingPage(iLandingPage)
+  {
+  }
+protected:
+  void push(Channel * c) const override;
+  virtual uint8_t bLength() const override;
+private:
+  constexpr static uint8_t k_platformCapabilityUUIDSize = 16;
+  uint8_t m_bReserved;
+  uint8_t m_platformCapabilityUUID[k_platformCapabilityUUIDSize];
+  uint16_t m_bcdVersion;
+  uint8_t m_bVendorCode;
+  uint8_t m_iLandingPage;
+};
+
+}
+}
+}
+
+#endif