GSA provides lines of similar items to meet particular end-use requirements under the GSA stock program, special order program (SOP) established source, and the Federal Supply Schedule program. Although these similar items may differ in terms of price, quality, and essential characteristics, they often can serve the same functional end-use procurement needs of the various ordering agencies. Therefore, in submitting requisitions or placing delivery orders for similar items obtainable from GSA sources, agencies shall utilize the source from which the lowest cost item can be obtained which will adequately serve the functional end-use purpose.
41 C.F.R. §101-26.100-1