Leigh Elliptical Guidebush - 7/16" OD (included with most Leigh jigs)

Leigh dovetail jigs use a combination of a dovetail or straight bit with a guide bush, rather than a router bit with a bearing. A 7/16" (11.1mm) guide bush can fit into a smaller space than most template style router bits, these will generally have a larger bearing size.
The Leigh guide bushes have an elliptical shape to them, which gives adjustability when the router bit is sharpened, and the diameter of the bit has been reduced, rotate the guide bush to compensate when doing finger joints.
Generally this feature is only used for finger joints, as it is easy to use the jig to make the required adjustments for the other joints.
The e7 is a 7/16" guide bush comes with the D4R and Super Jigs as standard, and is also apart of the RTJ400 and R9 accessory packs.