I used Harbor Freight pistons at first and was happy with them. I ordered it because I was able to get free shipping during the ordering process. They arrived, I opened the package and was disappointed with their size. I should have checked the description and converted to inches before purchasing. They are so small that they must have been made for model making or electronics because a carpenter couldn't use them. I will keep them as they seem to be of good quality and I'm sure they will come in handy for a future project.