will this hold an iPhone 4? Are the dimensions given on the website interior or exterior measurments?

I have an iphone 4. the only way it fits is if you stretch the flap cover really tightly over the top of the phone. it will not fit sideways and you will not be able to use the ear phone jack or have a cover/case on the phone. but it can be done (with the 4 not the 5). just make sure the Velcro latch is firmly attached so it wont open accidentally.

Can somebody explain how the magnetic mechanism works if you are wearing elastic band clothing (ie, no metal on the waistband)?

It has a magnet on the front pocket part and on the back piece, so in essence it sticks to itself. I always wear elastic waistband shorts with mine and love it!!!

would the mini hold a deck of playing cards

It should. Not sure how much other things because I gave it away as gift. I would have taken a picture for you with the cards in it. Great bag or you can get the regular one and it will hold the cards and other things like keys, money, credit cards, gum, etc.

will it fit on my collar of my shirt nightgown etc? I don't wear pants that much...

Yes it will work but depends on what you put in it. If it heavy it may pull down on your collar but with laying down it should be fine. I have 3 of them and love them. The closer is strong and stays closed plus the magnet is strong and stays closed no worry there. I hope this info helps you. You will not be disappointed.

Item Package Dimensions L x W x H	7.48 x 4.72 x 0.91 inches
Package Weight	0.06 Kilograms
Item Dimensions LxWxH	3.46 x 0.59 x 4.13 inches
Item Weight	2.08 Ounces
Brand Name	Running Buddy
Model Name	Running Buddy Mini
Color	Mini Blue (3.75" x 4")
Material	Dri-fit
Suggested Users	unisex-adult
Manufacturer	Running Buddy
Part Number	1002MB
Style	Pouch
Size	Small

Fanny Pack Waist Pouch - Water-Resistant Gym Belt - Magnetic Closure Waist Belt - Bounce-Free Fit Fanny Pack for Men - 3.75 x 4 in, Mini Blue

Description

Specifications

Common Questions