The "Semi-sealed" in this name is what the bearing community calls "sealed mechanism". In this case, they are cartridge bearings with one of the sealed sides removed. Remembering that "Tioga" is only a marketing company, we will tell you that Sugino of Japan makes this bottom bracket.
It is a "dual adjustable cup with fixed length spindle" design, which permits fine lateral adjustments. The spindle is made of cast steel, that is nickel plated, after the bearing races are precision ground. This spindle uses cast Black steel nuts to fasten the crank arms instead of bolts that thread into the spindle.
A Black plastic water sleeve is included with this B/B, and makes a tidy yet inexpensive solution to B/B replacement. The spindle comes in only one length, which is 130mm, but the floating nature permits lots of adjustment. The weight of the Tioga MTB-SK, with nuts and sleeve, is 376 grams. $Price in Catalog