Windjammer Capital Investors has purchased Advanced Instruments LLC, a maker of medical test equipment, for an undisclosed amount. The deal marks as the sixth investment from the buyer’s $726 million Senior Equity Fund IV.

Advanced Instruments designs and manufacturers laboratory test devices used across the microbiology, pharmaceutical, clinical, food and dairy, and biotech markets. The target touts its ability to measure osmolality with its freezing point depression technology, used to make devices like the A2O Advanced Automated Osmometer. Norwood, Massachusetts-based Advanced Instruments was founded in 1955 and now serves its clients in more than 90 countries under the Advanced Instruments, Fiske and Mart Microbiology brands.

Windjammer is a middle-market private equity firm that typically invests $50 million to $200 million in businesses that have up to $50 million in Ebitda. The buyer has offices in Newport Beach, California and Waltham, Massachusetts with approximately $2 billion in committed capital. While Windjammer is currently investing from its fourth senior equity fund, the middle-market investor recently sold Infinite RF Holdings Inc. (IRF), a supplier of adapters and cable connectors, to Genstar Capital. In 2015, Windjammer purchased Heritage Food Service Group, a distributor of repair parts for commercial kitchen equipment.

Medical device companies continue to receive strong buyer interest. Genstar-backed Tecomet Inc. purchased Mountainside Medical, a maker of endoscopes and laparoscopes; Johnson & Johnson (NYSE: JNJ) agreed to buy Abbott Laboratories’ (NYSE: ABT) eye-surgery equipment unit; TPG Capital acquired Beaver-Visitec International, another eye surgery device maker; and  Zimmer Biomet Holdings Inc. (NYSE: ZBH) agreed to purchase spinal surgery device producer LDR Holding Corp. (NYSE: ZBH).

The outlook for M&A in the healthcare sector was much more positive in August than it was earlier in 2016, according to Mergers & Acquisitions’ Mid-Market Pulse (MMP), a forward-looking sentiment indicator, published in partnership with CT.