metamask-extension/shared/constants/hardware-wallets.js

/**
 * Accounts can be instantiated from simple, HD or the two hardware wallet
 * keyring types. Both simple and HD are treated as default but we do special
 * case accounts managed by a hardware wallet.
 */
export const KEYRING_TYPES = {
  LEDGER: 'Ledger Hardware',
  TREZOR: 'Trezor Hardware',
};