Rather than the fabrication plant spending the time and taking space to assemble the required various additional materials, an Ancillary Pack purchased pre-assembled can be easily transported to site.
Various pre-set combinations of ancillary items can be supplied. Often a plant will order lower storey, upper storey or other regularly required standard combinations.
Although there seems to be a multitude of possible combinations varying according to the particular job, experience shows in fact there is little difference.
The removal of the fabricator’s hassle to make up each pack each time is avoided by an occasional marginal oversupply.
The alternate option is that that plant’s standard packs are on the small side and a few additional pieces may be thrown on the truck rather than assembling the entire requirement.