API 16A is a specification for Blowout Preventer (BOP) equipment used in oil and gas drilling operations. A Single Ram BOP is a type of BOP that has one hydraulic ram element, which is used to seal off the wellbore in case of an emergency or unexpected pressure surge.

API 16A Single Ram BOPs are designed to meet certain performance requirements, including pressure rating, temperature rating, and material requirements. They typically have a pressure rating of up to 15,000 psi and are available in sizes ranging from 7-1/16" to 21-1/4". Single Ram BOPs are typically used in drilling and completion operations, and are typically installed in stacks with other BOPs and associated equipment.

API 16A Single Ram BOPs are designed to be durable and reliable, with features such as quick-closing hydraulic systems, high-pressure seals, and rugged construction materials. They are also designed to be easily maintainable and repairable, with replaceable parts and easy access for inspection and maintenance.