UPS has announced it has reserved 125 Tesla Semis, the new electric Class 8 truck that was recently unveiled by Elon Musk.

This tops the recent 100-truck order announced by PepsiCo in November and represents the largest publicly known order for the electric truck yet.

The new tractors will join UPS’s alternative fuel and advanced technology fleet, comprised of trucks and tractors propelled by electricity, natural gas, propane, and other non-traditional fuels.

The first Tesla Semis are expected to roll off the assembly line in 2019, but UPS might not see all of its trucks right away as Tesla has a history of slowly ramping up production of its vehicles. The company only managed to produce 260 of its new Model 3 electric cars in the third quarter of this year. The Model 3 was announced in 2016 and was also initially sold through a reservation system.

The base model Tesla Semi is priced at $150,000 while a version with advertised 500-mile range begins at $180,000. It costs $20,000 to pre-order either model of Tesla Semi -- unless a buyer opts for the special edition Founders Series Tesla Semi, which costs $200,000 to reserve and buy.

“For more than a century, UPS has led the industry in testing and implementing new technologies for more efficient fleet operations," said Juan Perez, chief information and engineering officer. "We look forward to expanding further our commitment to fleet excellence with Tesla. “These groundbreaking electric tractors are poised to usher in a new era in improved safety, reduced environmental impact, and reduced cost of ownership.”