What are these Lowrance FF parts?

I've never used a fish finder before, but just got a Lowrance Hook2-4x. What are these two white parts (in the same bag as the fuse/fuse keeper)? The bare-bones manual makes no mention of them.

Also, where can I buy a battery in a brick and mortar store (in SF/Daly City)? First thought was Home Depot, but it doesn't look like they carry them in store. West Marine maybe?

White caps are for crimping wires together. 
Any battery or radio shack type store will have the battery you need.  Just select the size you want.

 
  Do you have a "Batteries Plus" in your area?  Use Amazon?  Prime shipping, you can have a battery in 2 days!

In Lowes/Home Depo, Ask for a Home Alarm Battery
Not where you would expect them
;0)

Got it. Thanks!

I’m guessing you have never done electrical wiring? I started using the connectors in the photo. Please do a little research and be sure of your wiring job, a few kayaks have been damaged with faulty wiring jobs, not mine but I know of a few.

If you're willing to go unorthodox, an 8 cell AA array should get you 4+ hours on your FF if I've done my math right, although if you want to use rechargeables you may need 10 or 12 cells. If you do go with NiMHs, get them from Ikea.

Going even weirder, you could get a 4S lipo from an RC hobby shop. 2000mAH should get you 5+ hours in a 7 ounce package that fits in a phone drybox.