A system comprising - a preform having a neck configured for an axial insertion of a gripping device wherein there is provided a circumferential step in an inner surface of the neck, said circumferential step being formed by the transition of the inner surface of the neck between a first part having a first diameter and a second part with a second diameter smaller than the first diameter so as to have a shape complementary to said circumferential step of the gripping device and to form the only end abutment position against the gripping device during the axial insertion, wherein the zone of the circumferential step on the preform neck is at about 4 mm from the neck ring base defining the base plane of an outer neck ring surrounding the preform, and wherein the first part extends from the mouth of the neck up to the circumferential step, and the second part extends from said circumferential step up to the neck ring base, and - a gripping device of a preform or container provided with a neck, comprising: a body apt to be positioned coaxially inside the neck, having an end portion, members (63, 64) configured to frictionally engage the inner surface of said neck in order to block said preform or container integrally with the gripping device, characterized in that the end portion has a first zone with a first diameter and a second zone with a second diameter smaller than said first diameter, and an interconnection zone therebetween forming a circumferential step, configured to abut against a circumferential step inside the neck of the preform and with a shape complementary to said circumferential step of the gripping device, so that the gripping device is apt to be inserted into necks with a different length of different preform formats so that plane under the neck ring of the preforms is always located at the same plane, whichever the format is. - a preform having a neck configured for an axial insertion of a gripping device wherein there is provided a circumferential step in an inner surface of the neck, said circumferential step being formed by the transition of the inner surface of the neck between a first part having a first diameter and a second part with a second diameter smaller than the first diameter so as to have a shape complementary to said circumferential step of the gripping device and to form the only end abutment position against the gripping device during the axial insertion, wherein the zone of the circumferential step on the preform neck is at about 4 mm from the neck ring base defining the base plane of an outer neck ring surrounding the preform, and wherein the first part extends from the mouth of the neck up to the circumferential step, and the second part extends from said circumferential step up to the neck ring base, and - a gripping device of a preform or container provided with a neck, comprising: a body apt to be positioned coaxially inside the neck, having an end portion, members (63, 64) configured to frictionally engage the inner surface of said neck in order to block said preform or container integrally with the gripping device, characterized in that the end portion has a first zone with a first diameter and a second zone with a second diameter smaller than said first diameter, and an interconnection zone therebetween forming a circumferential step, configured to abut against a circumferential step inside the neck of the preform and with a shape complementary to said circumferential step of the gripping device, so that the gripping device is apt to be inserted into necks with a different length of different preform formats so that plane under the neck ring of the preforms is always located at the same plane, whichever the format is.