Inclusion Criteria:
* Subject is ≥ 18 and ≤ 80 years of age.
* Subject has a previously untreated, ruptured or unruptured, saccular intracranial aneurysm 5mm or more in diameter for which the clinical decision to treat with Penumbra PC400 embolization coils has been made independent of the decision to enroll the subject in the study described in this protocol.
* The decision to undergo the coiling procedure is made independently of and prior to participation in the research.
* Subject has a baseline Hunt and Hess Score of I, II, or III.
* Subject must be considered by the treating physician to be available for and able to complete all follow-up visits.
* Subject has not been previously entered into this study.
Exclusion Criteria:
* Subject is \< 18 or \> 80 years of age.
* Subject has a baseline Hunt and Hess score of IV or V.
* Target aneurysm is dissecting, fusiform, blister-like, mycotic, tumoral, or AVM related.
* Target aneurysm maximum diameter is \<5mm
* Target aneurysm was previously treated via clipping or coiling.
* Target aneurysm is deemed by the treating physician to be unsuitable for coiling or unlikely to be successfully treated by endovascular techniques.
* Target aneurysm has not been confidently determined by the treating physician to be the source of SAH.
* Planned use of a flow diverter (Surpass, Pipeline, Silk, FRED, p64, etc.) or intrasaccular device (WEB, Artis, Medina, etc.) as a component of the target aneurysm treatment plan.
* Intended use of a coil-assist stent as a component of the target aneurysm treatment plan, unless stent is used for bailout purposes.
* Subject has a known, untreatable hypersensitivity to contrast dye, iodine, hydrogel, or any other component of the treatment device.
* Subject has a contraindication to heparin or aspirin.
* Subject has vascular anatomy/tortuosity preventing access to the target aneurysm.
* Subject is unable to undergo DSA or DSA is determined unsuitable or outside standard of care by the treating physician.
* Subject has a serious or life-threatening comorbidity that could confound study results.
* Subject is at high risk of noncompliance due to a history of substance abuse, psychosocial issues, etc.
* Subject is unable to complete scheduled follow-up assessments due to comorbidities, geographical limitations, or a life expectancy of less than 18 months.
* Subject is pregnant, breastfeeding, or plans to become pregnant prior to completion of follow-up.
* Subject is enrolled in another device or drug study in which participation could confound study results.
