Just the method: how the observation feed is measured, what it excludes and why, and the sampling caveats. Buy this if you want to judge the feed before buying it.

Paid over x402 on eip155:8453. Unpaid requests return HTTP 402 with a PAYMENT-REQUIRED header; the response body is the deliverable once payment settles, so the artefact arrives in the same HTTP response that is paid for. Price: 0.1 USD in USDC to 0x71aa2941B023e27532604B55A3c999601128CB4d.