Do you have a RV steps that droop when you step onto them? I used to until I started putting blocks of wood under the steps. I kept a variety of pieces of 2x4 and 1x4 lumber cutoffs to put under the steps when we were parked. These work great, but are a little inconvenient at times and sometimes you can get just the right height.
I found the answer at Camping World. At first I thought I really didn't want to "waste the money" on something I already had -- lumber. After seeing them a few times, I decided to buy one of their Save-A-Step screw jack step supports. It is two base plates separated by a big screw. Screw the jack up or down to just the right height of your step.
Because I am usually parked where my steps are low to the ground, I bought the shorter jack in the first picture below. Sometimes my steps are higher up due to the ground we camp at. I am going to get the taller jack in the second picture for those times.
Of course I can still put a piece of 2x4 under a jack if my height still isn't just right. The nice thing about the Save-A-Step jack is that it allows me to create a tight fit between the bottom of the step and the ground. No more slipping "lumber". No more, almost tight steps.
Just click on one the RV Step Stabilizer link below. Scroll down the page to see them all