Easy boat mooring! Simply hook the hook onto the underwater rope and attach it to the oar. Multiple units are available, so please inquire. (Please note that it may take some time depending on stock availability.) The rubber part is 28cm long. It will be shipped in the first image's state, and you use it by threading it through the hole as shown in the second image. It will be more secure if you do it like the third image. Shipping will be via Letter Pack Light. Please inquire if you need multiple units. Available for immediate purchase.