This is a double beam dial/counter type height gauge. UPS brought mine today. Is accurate to the two standards and 1-2-3 block I used to test it.
The part # is 621-8418
but enter it as BK621-8418 and the sale price of 129.95 shows up
This is good through 2/28/2012 according to my sale flyer.
Also free shipping through the end of January code: NCCJAN
That's right, an 18" height gauge brought to your stinken door for $129!