I need something to gage the waterproof rating off of, what would the waterproof rating of a plastic bag, and what is the waterproof rating of a cotton T-shirt?

Tech Specs:

Material:

[Shell] Active 10/10 nylon; [Lining] mesh 

Insulation:

None 

Waterproof Rating:

10K 

Breathable Rating:

10000g 

Core Venting:

Underarm zips 

Pockets:

2 Hand-warmer, 1 front stash, 2 chest, 1 pass pocket, 1 inner utility pocket 

Seam Taped:

Yes, fully 

Powder Skirt:

Yes, stashable 

Hood:

Yes, removable 

Zip-in Compatibility:

No 

Recommended Use:

Snowboarding, park/pipe 

Country of Origin:

China