The presence of free air within the peritoneal cavity is known as pneumoperitoneum. In 85% to 90% of cases pneumoperitoneum is due to perforated bowel of various aetiology which includes perforated peptic ulcer. typhoid. trauma. https://www.roneverhart.com/Western-Digital-Ultrastar-DC-HC550-WUH721816ALE6L0-0F38460-16TB-7-2K-RPM-SATA-6Gb-s-512e-ISE-3-5in-Hard-Drive/