Spectra Precision RC601 Remote Control The Spectra RC601 remote control is designed to work with the HV101, HV301, HV301G, HV401, HV601, LL100, LL300 and LL400 laser Levels. It gives you remote control over the units so you can perform one man operations with a grade rod and receiver. Gives access to LL300 single-axis slope mode. Allows one - person grade matching with LL400. The RC601 uses IR technology to enter Slope / Grade into any of the listed Rotary Laser Levels.Adjusts speed in select Models. Allows Laser to use Manual Mode and HV models to use Chalk line or Dither mode Function.