i use these locks. time savers especially in the dark. can create a custom combination.
A stupid lock for stupid people. If you want a very mildly secure lock for things like gym lockers that's super fast to open, get something like this Master lock. I have one. I can open it with it held behind my back. It's super quick and easy to unlock, unlike wheel based or, especially, dial based combination locks, which I ALWAYS overshoot with and have to try 2 or 3 times...
$8 for that Master lock. Doesn't need batteries. Can easily be opened blindfolded in a matter of 2 seconds. It's really a great lock for things that only need basic security, and far better than some stupid gimmicky battery powered "smart" lock.
I don't know any bypass or decode for the Master Lock 1500iD Speed Dial. It's not the most rugged lock in the world, anyone with bolt cutters could pop it, but it does use a mechanical hashing function for the combination that is clever.
Maybe someone else here knows one?
In my relationship, I'd just tell my sub that she isn't allowed to use/touch it without getting my explicit permission, and her desire to obey my wishes will prevent her. Also, no real reason to punish unless she has disobeyed and that is your dynamic, but for most subs that I know, a firmly worded "You are not allowed to touch this or it will displease me" is all the incentive/threat you need.
That said, if the fun of it is the challenge of having it at her place and her getting to try and get at it, get a box, agree she isn't allowed to break the box to get in, and use a Lock . These can't be picked using any standard technique, and the challenge of getting in without breaking anything should serve as a good one. Alternately, you could just lock the plug end in a box with one of these, but either way you could keep the game element of her getting to try and get at it, while being much more confident that she won't actually get at it.
https://www.amazon.com/Master-Lock-Combination-Assorted-1500iD/dp/B002TSN4SQ
I have a lock like this for work. It works like a D-Pad on a controller
I went with one of these AR locks/mounts. And I lock it with one of these directional-type padlocks. Might not be the most secure padlock available, but I won't have to fumble with finding a key or spin dialing a combo - especially in the dark.
Locks:
Get three of these: http://www.amazon.com/Master-Lock-1500iD-Combination-Assorted/dp/B002TSN4SQ Why? They're quick to open, and you can open them without looking (i.e. in the dark.) You'll thank me later.
Writing materials:
Believe it or not, you're actually going to want to take notes sometimes, or make rosters, or whatever. Bring some small notebooks that have plastic on the front & back to make them somewhat sweat-proof. (I used these: http://amzn.com/B0013C7WFA and privates were legit trying to buy them off me. I'm sure there's a five-star brand version of those that isn't as expensive out there somewhere.)
Also bring normal paper for letter writing or whatever. Pens. You will lose some. Bring extra.
They do have some of this stuff at the PX, so don't go crazy if you need an extra notebook or anything, but the less you have to buy there the better.
Socks:
Addressed well by others. The prices in the PX are reasonable for socks, so just buy the ones offered there.