If you are intending to use the MultispeQ device to measure absorbance, transmittance, or reflectance in cuvettes then you may want the MultispeQ cuvette holder. Note that once you install the cuvette holder, the calibration for most of the plant measurements go out the window (photosynthetic efficiency, chlorophyll content, etc.) - so be aware you may need to recalibrate if you install a cuvette holder.
See images below for install. Unscrew hinge from the case, insert cuvette holder, and install longer screws in their place. The metal screws go directly into plastic, so be very careful not to over tighten! Once complete, force the clamp closed with a piece of duct tape - it should be pretty tight because even small adjustments between measurements could change absorbance values.
That's it! In the next version of the chrome app (available very soon as of 4/14/2015) You can also now use the 'spec mode' tool in the PhotosynQ Chrome app (go to "Tools" --> "spec mode") - this is a really easy way to get started taking absorbance measurements, and includes the ability to save a blank.