There is a difference in the with of the cylinder for the large frame, I had this confusion when buying one. Found the info on the web. You just need to do some searching.
Item Name: Item Gone: FS FN 545
Location:
Item is for: Sale Only
Sale Price: $875
Caliber: 45
Willing to Ship: No
Bill of Sale Required?: No
Item Description: BNIB FN545 for sale only, no trades please. Never fired, original owner.
Pictures:
Item Name: Item Gone: FS/FT Arex Zero Compact 9mm
Location: EATONTON
Zip Code: 31024
Item is for: Sale or Trade
Sale Price: $550
Trade Value or Items Looking For: $550
Caliber: 9mm
Willing to Ship: No
Bill of Sale Required?: No
Item Description: Arex Zero 9mm, Nickle plated slide, hogue...