I've been asked to help a lady get and install an entrygard -- truth mechanism. The only numbers I see are 358 IR. In the house, the window in hinges and crank are/is on the left and the window swings out from the right. The longest arm is 9." The link that projects from the crank is 4.5" and ends in a clip. Some one said I need a WI 1510. Am I on the right track? Would also appreciate any installation tips in addition to what's been posted already.