Tumax DPT386AFZ Instruction Manual:
Tumax DPT38xAFZ Instruction Manual:
It seems that the Bower SFD926 is actually a re-branded Tumax DPT386AFZ.
It also seems that the Tumax DPT386AFZ is part of the Tumax DPT38xAFZ series, which in turn are available re-branded as:
Opteka EF-600 DG Super;
Vivitar DF 383 Series 1;