Pocket Watch Vest Chain

If my husband wears his pocket watch in a vest pocket watch, how long a chain should I buy for him?

I'll buy a chain off eBay and see a wide range 4-5 "14. I think that the more suitable (like a 12 to 14) but it is not a tall or long waisted. I gave him two pocket watches to holidays past, including a Patek Philippe.

The standard length is 13 inches.

A Bit of Earth (The secret garden)