def units_converter(from_units='ip', **kwargs):
    """ Converts IP values to SI units

    Parameters
    ----------
    from_units: str
        specify system to convert from
    **kwargs : [t, v]

    Returns
    -------
    converted values in SI units
    """
    results = list()
    if from_units == 'ip':
        for key, value in kwargs.items():
            if 'tmp' in key or key == 'tr' or key == 'tdb':
                results.append((value - 32) * 5 / 9)
            if key in ['v', 'vr', 'vel']:
                results.append(value / 3.281)
            if key == 'area':
                results.append(value / 10.764)
            if key == 'pressure':
                results.append(value * 101325)
    elif from_units == 'si':
        for key, value in kwargs.items():
            if 'tmp' in key or key == 'tr' or key == 'tdb':
                results.append(value * 9 / 5 + 32)
            if key in ['v', 'vr', 'vel']:
                results.append(value * 3.281)
            if key == 'area':
                results.append(value * 10.764)
            if key == 'pressure':
                results.append(value / 101325)
    return results
