Current transformers are available from stock in a wide choice of styles and ratings. All are high quality metering standard items of class 1 accuracy unless otherwise stated.
Ring type CTs are the lowest cost option, but are often impractical in retrofit applications. Split types offer significantly greater flexibility in this respect.
Voltage output split CTs are a new development, and provide additional advantages in terms of reduced size and weight, and longer cable runs for new meter connections. This type can only be used with a compatible meter type however.