If you use a lot of different exposure suit and gear configurations

[divezonescuba]

This may help keep your weights and weight configurations straight and prevent you from having to keep reinventing the wheel every time you change configurations. Salt or fresh; 3, 5, 7, light or heavy drysuit undergarments; backmount or sidemount; one or two tanks; one, two, or three deco tanks, AL or steel, etc.

 

[MB NZ]

I once dived with a guy who would change between a drysuit and a wetsuit on the first and second dives of the day. He was an absolute nightmare, either underweighted or overweighted on every dive. All over the place. The worst dive buddy I've ever had. He could have used something like this!

 

[PfcAJ]

Weighting for empty deco tanks will make you needlessly heavy. They can be ditched or sent up the ascent line when empty.

 

[divezonescuba]

That was primarily for trim purposes as weight placement can be different between 0, 1, 2, 3, etc non-primary tanks for deco, travel gas, stage purposes. The total weight is the same regardless of non-primary tanks and is based on the exposure suit, water type, type of rig, primary tank type, measurement system, and plate material.

For example, with AL80 twinsets in salt water in 5mm, I use either 16 lbs or 8 kg regardless of whatever else I am carrying. But the position of the weights will change.