This read-write integer is the same average-frame-size estimate as cktFrameSize but applied to the reverse direction of the circuit, again defaulting to 280 bytes if not explicitly configured. Because ATM traffic contracts and cell-rate calculations can differ by direction on an asymmetric circuit (e.g., a client site sending small acknowledgment frames while the server site sends large data frames), this object lets the switch model each direction independently rather than assuming symmetric traffic. An engineer provisioning a circuit where the downstream (to-customer) direction carries large 1400-byte video frames but the upstream carries small 64-byte control frames would set cktRFrameSize to reflect the smaller reverse-direction average.