The Surge-Trap Type 1 STZ Series is Mersen’s premium-featured surge option to be installed at service entrance locations and for protection of the most critical loads. Designed with industry leading Mersen TPMOV® Technology, the STZ series is ideal for industrial and commercial environments and does not require additional overcurrent protection. The STZ series has mounting options (internal and external/ in enclosure) suitable for both new construction and retrofit applications.