The 4.5 Glue-on Control Head Only mount kit is perfect for fish finder control screens up to 5" inches in size, E.g. Humminbird Helix 5, Lowrance Hook2 5, etc., and will also support some 7" inch screens such as the Lowrance 7 Ti2.  Purchase the 7.5 model for 7" inch screens and above - here:  
 
https://www.fishfindermounts.com/product-page/7-5-glue-on-control-head-only-7-to-12-screens
 
Glue/Adhesive is sold separately, and must be sourced from a third party. For PVC fabricated boats we recommend: CLIFTON URETHANE GLUE as seen at this link: https://www.nrs.com/product/1901/clifton-urethane-adhesive-la-4123 ; and for Hypalon boats we recommend the STABOND UK - 148 adhesive as seen at this link: http://www.nrs.com/product/1903/stabond-adhesive . If you are in Canada, check out the Aquabatics website for some good options here:  https://aqoutdoors.com/search?q=clifton The Scotty's glue on mount in this kit is fabricated from a flexible PVC.