I "discovered" PEC tools of California and was so impressed I bought some of their stuff to put it to the test of daily use.  I am still impressed and I now recommend PEC's premium line of layout tools. 

If you are going to use my method of laying out dovetails (taught to me by Allen Peters) then you will need some dividers. I recommend using two dividers for marking dovetails: one to mark the half pins and one to mark the full tails.  I prefer the 4"dividers because I find them more comfortable to use than the larger sizes.  In addition to dovetails you will find lots of uses for dividers.  These PEC Spring Dividers are really good quality and priced right.  I highly recommend them.

•  4 inch long dividers.

• Points are tapered and sharp.

• Sharp knurling on the adjustment nut for easy gripping.

• Split nut adjustment screw allows for quick setting.

• Polished Natural Steel Finish