The Durston D4 'Stacked Mill' is the larger of the 2 Durston Double Rolling Mills, the smaller being designated as the D2. The D4 has rolls that are 28 mm wider, has an extra set of extension rolls, and is furnished with 2 lever handles: one for heavy rolling with a gear ratio of 11 to 1, and the other, with a gear ratio of 5 to 1 for lighter rolling at twice the speed. Changing the handle only takes a few seconds.

The two sets of extension rolls have between them 7 half-round grooves. Additionally, one of the main wire rolls has 3 more half-round grooves for a total of 10 half-round grooves on this mill.

As with the D2 mill, the D4 has two sets of rolls, one for sheet (with extension rolls for halfround shapes) and the other grooved mainly for square wire with a small section forming half-round wire. The wire rolls also have extension rolls. The rolls are set in high quality, maintenance-free bearings and are guaranteed for life. Rolls are of the highest quality alloy steel hardened to 63 / 64 Rockwell C and ground to perfection. Single, calibrated dial is in a central, easy-to-read location. Extremely versatile and very rugged in construction, this machine is very simple to use with full control over roll passes for both sheet and wire. Made in England.

• Extension rolls (2 pair) have a total of 7 half-round grooves 1.5, 2, 3, 3.5, 4, 6, and 8 mm
• Roller Dimensions 158 mm wide x 60 mm dia.
• Gear Ratio 11:1or 5:1 for flat and 5:1 or 2.2:1 for wire rolls
• Thickness Capacity 7 mm
• Flat Section 158 mm wide
• Wire Section 120 mm wide with 19 square grooves, 10 to 1 mm, plus 3 half-round grooves: 5, 6, and 7 mm
• Shipping Weight 220 lbs.