function buyAndSwap721WETH(
  uint256 vaultId, 
  uint256[] memory idsIn, 
  uint256[] memory specificIds, 
  uint256 maxWethIn, 
  address[] calldata path,
  address to
) public nonReentrant {
  require(to != address(0));
  require(idsIn.length != 0);
  IERC20Upgradeable(address(WETH)).transferFrom(msg.sender, address(this), maxWethIn);
  INFTXVault vault = INFTXVault(nftxFactory.vault(vaultId));
  uint256 redeemFees = (vault.targetSwapFee() * specificIds.length) + (
      vault.randomSwapFee() * (idsIn.length - specificIds.length)
  );
  uint256[] memory amounts = _buyVaultToken(address(vault), redeemFees, maxWethIn, path);
  _swap721(vaultId, idsIn, specificIds, to);

  emit Swap(idsIn.length, amounts[0], to);

  // Return extras.
  uint256 remaining = WETH.balanceOf(address(this));
  WETH.transfer(to, remaining);
}
