The G.R.I. series of commercial and industrial switch sets offers the installer two choices: The 400 series incorporates hidden terminals, inset into the recessed back to provide tamper resistant installations. The 410 series has the standard terminals located on the side of the switch. Both options give the installer a regular gap of 1 1/2" while the wide gap version is 3", which cover the various types of steel door and frame conditions found at every commercial and industrial site.