There are two basic types of Shaft End Covers (SEC) for our 3100 and 5100 series gear products.  The SEC Code is determined by the entire 3 digit designation where the first digit always determines the rotation.

Type I - With a single outboard ball bearing or without.   This option gives you flexibility with your unit enabling you to utilize the unit for side load operations depending on your application.

Type II - Without outboard bearing.  This configuration is shorter in length (by up to 1") and should be chosen when side load operations are not a consideration for the unit.