In the context of premises electrical wiring, an LB is a generic term for a conduit body that makes a right angle turn, with a fitting opposite the cover. It looks like this:  There are also different configurations going straight, out either side, or with three fittings.

Specifications:

• SKU: CBLB012
• AVAILABLE SIZES: 1/2" , 3/4" , 1" , 1 1/4" , 1 1/2" , 2" , 2 1/2" , 3" , 3 1/2" 4"
• BRAND NAME: DUSTAR 

• REMARKS: This item is open for a large volume of sales. For request of distribution email CLICK HERE.