what is the best marine grade heat shrink tubing out there today ?
or is all of it basically the same ?
TIA for those knowing more about this than me.

I've used alot of it with the glue inside. All of it seems fine over the years. The only failures I've seen were actually factory splices. I worked at FCA in the electrical lab. Saw a few bad splices. These were sonic welded. When they got hot from the poor conection the glue would flow. A few times it weeped between a eyelet and stud ground causing a poor ground connection.
Doug

These.guys have high-quality electrical supplies including the internal adhesive heat shrink tubing.

https://www.westmarine.com/ancor-ad...andware_net__WestMarine__products__en_US

I buy mine from NAPA. So far, so good.

I have a butt load of various sizes, 3 or 4:1 shrink ratio, All adhesive lined. 1/8" up to 3/4? (0/0 battery cable& lug size)
Some are 3-4ft long, some are cut down smaller lengths
PM me your needs and I'll see what I have

I am not aware of any heat shrink specifically marine rated, but as others have mentioned, the variables are glue options, shrink ratio which effects final thickness and flexibly I suppose, and operating temps would seem to be the main ones for automotive use..
i have bought it locally in Florida for decades, and after paying for it and before walking out the door. the "helpful" cashier wads it up and stuffs it in a bag, nearly ruining it by all the induced wrinkles it puts in the heat shrink.
I have a few clear plexiglass 4' long tubes I store my assortment of heat shrink in to be able to retrieve the assortment of colors, diameters and lengths needed for whatever project I'm working on.

Take a look at Aircraft Spruce mail order aircraft parts company for some good heat shrink: scope:, if they are allowed to sell for aircraft use

that was one place i never thought of.
around here, "marine grade" has always been used to describe the shrink tubing with the "glue".
at the present time i don't need any, and the stuff i have seems to work good, so i will continue to use it until i need more. i have a multitude of sizes and colors, including battery cable size[s] in red and black.
i was just wondering if there were "better grade" products out there, other than the generic products from places such as NAPA, e-bag, and amazon.

The glue type heat shrink I have used in the past was nice in many ways, but I felt it was overly stiff once shrunk and made me concerned that repeated flexing would lead to eventual cracking of the heat shrink which I never observed.

i never really experienced any difference in flexibility between the regular heat shrink tubing, and the marine grade with the glue.
of course, i never tried a "flex test" trying to crack it either.
i might have to try that sometime, just because........

Ancor products are top notch. The adhesive shrink tube seals out water and everything else.

Shrink tube