SagsAway Supplemental Support | Use ONLY with Standard Insert for Deeper or Longer Sags (Posture Zone 1&rdquo;x8&rdquo;x18&rdquo;) Before you Order: 1" POSTURE ZONE is NOT used to fix an entire sagging mattress nor used for chronic back ailments. FIRST follow the 3 steps for using a "Standard" insert, evaluate your results and add Posture Zones ONLY if needed to target your remaining sag depth for a level sleeping surface. (do not over compensate for sag depth creating a hump) Posture Zones are used for Supplemental Targeted Sag Support when combined with a Standard insert on INNERSPRING or LATEX Mattresses only up to 14" thick. Most of our negative reviews come from using Posture Zones incorrectly. Some mistakenly choose them because of price  thinking an 8 x 18 insert will somehow restore their entire mattress. 3 WAYS to use a 1 Posture Zone: (1) extend the coverage length of a Standard unit for elongated sags often created from rotating a mattress. (2) target deeper sags usually in the hip area. (3) target a sag where you sit on the edge of the bed. Try One  Test Your Results. Instructions and a phone number are included. If you dont achieve the results others have, give us a call with your measurements. This is simple, you want to fill in your sag depth measurement to level your sleeping surface. For example, if you have a  sag and you use a 1 thick Standard, its going to be too much. If you have a 4 sag and use a 1.5 Standard Deep, thats not going to be enough. Some sags are simply too deep for this to work. Anything over 3 deep is not a sag, its a crater and its time to buy a new mattress. NOTICE: If you aren't sure of the type of mattress you have, find out first. DOES NOT WORK on Tempurpedic, Memory Foam mattress, air, water or sofa bed mattress because the effect of the support is absorbed rather than transferred. Amazon handles all returns within 30 days - less return shipping. (details below)