Those are MK mechanical retracts. They are pretty tough and don't need much attention, just make sure they are free of dirt at the movable parts.

The CRC super strut tool is the best tool for these retracts, you use it to straighten the struts in case you have a bad landing. I usually use two at the same time, one to act as a anchor, and the other to bend the struts. They were made by my good friend Frank Capone of CRC Products a number of years ago, he has since sold the business to Mark Burne (sorry for the mis-spelling) in Canada.

Adrian