About this publication
Terms of use.
This is an independent editorial resource, not a service contract.
Scope of information
The guides provide general decision support. Equipment instructions, product labels and requirements applicable to your location take precedence. Do not use the website to diagnose an emergency, certify equipment as safe or prescribe treatment.
No service relationship
Reading a page, using a tool does not book a contractor, create a professional-client relationship or authorize a third party to contact you. Any future referral service will have a separate, clearly described process.
Products and third parties
Product availability, conditions and manufacturer information may change. Verify the current details with the responsible organization before making a purchase. We do not claim to have personally tested products unless a page explicitly documents a real test.
Original content and corrections
The original text, diagrams and tools are an HBK publication. External materials remain their owners’ work. Our Resources page identifies the organizations behind the guidance.