From the Blue application website (so it depends on your credit rating, I know for a fact that the preapproved offers they send you has a preset fixed rate):
0.00% Introductory APR (0.0000% DPR) for Purchases either for the first 15 months, 12 months, 6 months or 6 months of Cardmembership, depending on our review of your application and credit history. Then, a variable APR of 12.24% (0.0335% DPR);14.24% (0.0390% DPR);17.24% (0.0472% DPR); or 19.24% (0.0527% DPR), depending on our review of your application and credit history.