The purpose of utilizing a chin rest is to fix and standardize the distance from the patient's eyes to the center of the blind spot mapping software screen.  Since the distance is now standardized and the technique is now standardized with the computerized software, one can now rely on the data generated for serial testing.   Chin Rest Specifications: Measurements for all models is determined by the distance from the base to the chin cup. Superior quality stands feature an all metal housing with Gliden Lock Clutch, which will not slip under pressure. HCRTMR Table Model with 6" Base Adjustable 11.5" to 15" (6 lbs).  This model is more portable than those that clamp on the table.  With increased portability, some stability is compromised.  If you are planning on utilizing a computer for  multiple tasks (patient charting, billing, report writing, blind spot mapping, etc.) this chin rest may work better for you.

HCRFMR Floor Model Adjustable 36" to 64" . Includes 12" Base If you don't have access to a computer for blind spot maping, this floor model chin rest works well if you are using the pen and paper method of mapping blind spots.

HCRD2R Double Screw Clamp Adjustable 11.5" to 15 (4 lbs) Clamp opening accommodates table thickness up to 2.5" This screw clamp on model is the most stable but slightly less portable.  This model can be unclamped and removed in less than 30 seconds if you need to use the computer for other applications.  This is the model I recommend if you can dedicate a laptop or PC to a few applications.  I have a dedicated station where I use the blind spot mapping software, hemifield stim software and Interactive Metronome software.