This experimental research is aimed to evaluate the consequences of the slack offered by after-market weblocking components (“comfort clips”) on the performance of three-point seat belts.

The tests were performed by simulation of a frontal impact at 50 km/h, recording chest and pelvis displacement of the dummy and variations in belt loading.

We tested all the devices on sale in Italy up to September 1989:​ each device has been tested five times, with a configuration of the restraint system according to Fiat Tipo.

The laboratory results show a very bad performance of the devices under the test conditions, with a mean increa= of E-20% for chest and 40% for pelvis displacement.

The most worrying finding was the breakage of the belt, in 7 cases over 35;​ in other 3 cases, there was severe belt incision.

All these laboratory data demonstrate danger in the use of these web-locking components.