Once installed, these collars are highly functional preventing the slippage of the oars out thru' the oar locks during a moment of inattention. These collars hold the oar at a proper position in the lock. The instructions are the most perfuctory and do not include any tips or techniques to make the cutting of them any easier, nor do they help the new user select the best place to install on the oar. Also, since it is difficult to change their position once they've been installed, there should be a caution notice should one be using closed ring oar locks to the effect that the locks must be on the oars before the collars are installed. The cutting is easy which is good because it's hard to determine how much to take off these to fit a standard size oar.