YES. A few cents make big $$$$ - One million Penney's is $10,000.00--- I learned about the piston the hard way! Last summer I installed a new AH -14 SEER- 4.0/ the used condenser at the time was a 3.5 -13 SEER - The piston I used was .076-- yesterday went to install new 4.0 -14 SEER R410A condenser-- did not get a piston with the new condenser- did not have a piston chart with me. I was think 410A piston is smaller than R22-- I guessed at the size- SH & SC low= undercharged-- put some gas in & inside split TD went down. - That is when I realized problem was size of piston. Piston chart calls for .080 - My brain was thinking 13 SEER 3.5 condenser & R22 - and was working on 14 SEER 4.0-R410A-- Lesson learned - when installing 1/2 system buy the correct piston with the unit- don't assume you will get piston with condenser any more.:vs_mad:Anything to shave a few cents off each unit.