Keep critical fiber links up with a singlemode SFP designed for 1.25 Gbps transport over distances up to 10 km. The Altronix P1SM10 is a practical fit for access-layer switches, edge aggregation points, and other network segments that need consistent optical performance without overbuying capacity you will not use. Its singlemode design supports longer-reach deployments than short-range multimode optics, making it a strong choice for campus interconnects, remote closets, and building-to-building runs. The compact SFP form factor helps preserve switch density while keeping the deployment model familiar for teams that standardize on modular optics. For infrastructure teams, the value is straightforward: match the optic to the link, keep the BOM disciplined, and avoid unnecessary complexity. When the requirement is stable 1.25 Gbps connectivity across a 10 km span, this module gives you a clean, purpose-built option for production networks where reliability and compatibility matter.