It is the abbreviation of Bridge Tied Load. It reverses the speaker both terminals to connect by using two amplifier circuits compared with a usual single amplifier. If without output coupling capacitor,it may has an advantage that output electric power quadruples.
Please choose according to customer's system configuration. In case of differential input form,BH7826FVM can be used, and in case of single input form, BH7824FVM/BD7830NUV can be used