The Ec/Ed tool holder is made specifically for the WM210v lathe. Which is 10mm (0.393) wider than the Aa, which gives it better clamping capacity. There is a comparison chart below where you can see the difference between them. Quick Change Tool Post Set has 4 holders for lathes with a center height of no more than 125 mm4.94? Recommended top slide width :55-70mm. Adjustable turning tool height :15mm. Ec Model : S/N:01013, Hole diameter : 18mm. Ed Model : S/N:01014, Hole diameter : 18mm. (Ec is made of steel, Ed is made of stainless steel). Tool post&holder with precision ...