This $100 (same day while you wait) service is to check current nitrogen level and if necessary add nitrogen (up to 4 shocks). Mobile service is available with an added fee. I use a powertank precise charge nitrogen system so that your shock seals do not get blown out accidentally. Our local dealer wanted to charge me $200+tax (back in 2018) to check my shock nitrogen psi and more to fill should it be needed (not much more, but still more) and then wouldn't promise it back to me for 4 weeks. I decided to purchase a professional setup and do it myself. I am now just looking to get back some of my investment and help others at the same time that do not want to pay $200+tax. :) Shrader valve or Fox needle valve types. For needle valve types add $50 extra. (These take longer to service)