The Laborator 138 was sold with at least for different heads (condenser, CLS 300, CLS 301 and CLS 1000). The condenser head is capable of holding the (optional) cold light drawers (very hard to find). If you have a standard condenser head, you might want to search for condensers on ebay (not quite easy) or - if you prefer diffuse light anyhow - one of the color heads (probably easier and cheaper than a full set of condensers). Simple opal glass will most probably not deliver an even light distribution, although I have never tried that.