Some backshells may have a Rib or Ribless option. The Rib feature is basically a smaller cable clamp opening, an example of this is listed below:
349501210 (WM13166-ND)
MX150 Backshell for Male Sealed Connector Assembly, 12 Circuit, with Rib
Rear View:
349501220 (0349501220-ND)
MX150 Backshell for Male Sealed Connector Assembly, 12 Circuit, without Rib
Rear View:
Summary
WM13166
349511210
34951-1210
0349511210-ND
034951-1210
34950-1220
034950-1220
349501220
900-0349510811-ND
900-0349511611-ND
900-0349500811-ND
900-0349501611-ND
900-0349510821-ND
900-0349501621-ND
900-0349502021-ND
900-0349511621-ND
WM12839-ND
WM12836-ND
900-0349500821-ND
0349501220-ND
WM23077-ND
0349510620-ND
WM12837-ND
WM13166-ND
WM12838-ND
WM20007-ND
0349490210-ND
0349490220-ND
0349480220-ND
900-0349490310-ND
349510811
349511611
349500811
349501611
349510821
349501621
349502021
349511621
349510610
349500610
349500821
349501220
349480210
349510620
349500620
349511210
349501210
349511220
349490210
349490220
349480220
349490310
2266-85071-0017-ND
2266-15-04-5404-ND
2266-15-04-5144-ND
2266-15-04-5424-ND
2266-15-04-5304-ND
WM21837-ND
WM9247-ND
2266-15-04-5364-ND
WM4337-ND
85071-0017
15-04-5404
15-04-5144
15-04-5424
15-04-5304
15045124
15045084
15-04-5364
15045404