This Sunny Boy Combiner Box, SBCBTL6, is a string combiner connecting up to 6 strings. This Combiner Box is designed for the use with transformerless SMA PV inverters. SMA touch safe Fuse holders are included. For additional information, see the ./pdf installation guide below. Note: he Sunny Boy Combiner is shipped without any fuses. For correct operation fuses have to be purchased by the installer.