# Custom device interface The custom device interface exposes host devices that belong to a Linux kernel subsystem. A custom device plug is described by these attributes: | Key | Value | Description | |------------------------|---------|-------------------------------------------------------------------------------------------------------------------------| | `subsystem` (optional) | string | The Linux kernel subsystem of the host devices to expose,
for example `input`, `tty`, or `usb`. | | `vendorid` (optional) | string | Restrict the exposed devices to those with this vendor ID,
quoted so it is read as a string, for example `"0403"`. | | `productid` (optional) | string | Restrict the exposed devices to those with this product ID,
quoted so it is read as a string, for example `"6001"`. | At least one of `subsystem`, `vendorid`, or `productid` must be set. Setting `productid` also requires `vendorid`, since a product ID is only meaningful within a vendor’s namespace. Plug owner: any regular SDK; not the system SDK. Slot: the system SDK provides a single `system:custom-device` slot. Other SDKs cannot declare custom device slots.