Chamfer ring for pipe coupling

A pipe coupling comprising:

• a rigid stiffener in a fixed position within a shell, said stiffener having an external diameter less than the internal diameter of a pipe configured to be secured by said coupling, wherein the stiffener includes a first groove and a second groove spaced apart from the first groove;
• a first O-ring positioned in the first groove and a second O-ring positioned in the second groove;
• an insertion sleeve movably coupled to the rigid stiffener, the insertion sleeve includes a body having an outer surface and an opening passing through the body, wherein,
• the body includes a cylindrical first section disposed between a second section and a third section, the first section has a maximum outer diameter of the body, the second section having a varying diameter along its length, and the third section having a varying diameter along its length,
• the opening includes a first region with a constant inner diameter and a second region with a varying diameter, wherein a maximum diameter of the second region is greater than the constant inner diameter;
• wherein the insertion sleeve is assembled on the rigid stiffener with the second region positioned closer to the first O-ring than the first region;
• and
• wherein the maximum diameter of the second region is greater than an outer diameter of the first O-ring.