This economical special holder allows an external power source to be used for 26cm long spectrum tubes. Fitted with 4mm safety sockets on black panel. This holder is fitted with bosshead which allows its clamping on any laboratory stand. Spectrum Tubes & Stand are not included.Requires the following equipment to operate:E.H.T. Power Supply - B8R02653E.H.T. Safety Experiment Leads - B8R07149Spectrum Tubes - B8R06989, B8R06986, B8A46539, B8R06991, B8R06990, B8A46565, B8A46553, B8R06992, B8R06832Retort Stand Base - B8A82004Retort Stand Rod - B8A82053