This sale is for a used but still excellent condition Mamiya C front lens cap, 50mm diameter for most common Mamiya C lenses that take 48mm filters.
This cap has obvious but only normal minor signs of use, and has a chrome Mamiya name on the front. It fits many of the Mamiya C lenses such as the blue spot 80mm f2.8, 135mm and 180mm lenses. Try finding another one – these are almost impossible to find.