3. Patients must have completed or withdrawn from CSLCT-SCIG-05-23 and wish to continue SCIg therapy; or, patients ineligible for CSLCT-SCIG-05-23 but for whom the Investigator believes SCIg may be a suitable form of Ig replacement, for reasons such as: poor tolerability of IVIg, difficult venous access, or, preferred route of administration.