3m 4200 Marine and a mounting plate if someday you may want to remove it.
3m 5200 Marine and a mounting plate if you do not ever intend to remove it.
Already been said if you mount a plate you can move or add transducers(good advice).
Can get 3m marine at Canadian Tire.
4200 has 1 in stock in Medicine Hat.
5200 has 6 in stock in Medicine Hat.
https://www.cabelas.ca/product/10099...mounting-plate
Shows in stock.
And you can also add a couple screws if you wish.
PS - I used a couple of screws plus the
4200 and it was still not easy to get off after I got the screws out.