This is a prospective, multicenter, observational study designed to evaluate the clinical outcomes of the Ranger™ SL paclitaxel-coated balloon, a type of drug-coated balloon (DCB), in the treatment of below-the-knee (BTK) lesions in patients with chronic limb-threatening ischemia (CLTI) in China. All enrolled patients will be followed for six months. Patients diagnosed with CLTI who undergo treatment with the Ranger DCB will be included in the study. The primary outcome is the incidence of major adverse events (MAEs).