> ## Documentation Index > Fetch the complete documentation index at: https://openrouter.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # ResponsesRequestServiceTier The service tier to use for processing this request. `fast` is accepted as an alias for `priority`. ## Example Usage ```typescript theme={null} import { ResponsesRequestServiceTier } from "@openrouter/sdk/models"; let value: ResponsesRequestServiceTier = "scale"; // Open enum: unrecognized values are captured as Unrecognized ``` ## Values ```typescript theme={null} "auto" | "default" | "fast" | "flex" | "priority" | "scale" | Unrecognized ```