Doesn't appear that is correct, or is it?
From their site and from the .45 ACP page:
GLOCK .45 ACP Magazine GLOCK pistols permit almost unrestricted compatibility of the magazines within a caliber. Standard magazines, for instance, can also be used for backup weapons.
GLOCK magazines have a stiff metal tube encased in the proven GLOCK high-tech polymer. This resists deformation – even when dropped from great height or exposed to extreme environment conditions.
MAG AVAILABILITY UPDATE: Due to the extreme demand since mid-December 2012, we have recently run out of the thousands of mags we had in inventory. We are accepting backorders and are working diligently with manufacturers to get more supply, but at this time are unable to provide a firm ETA as to when new shipments will arrive (most likely a 90-day minimum). Backorders will be filled on a first come/serve basis with current prices honored and you will NOT be charged until your order has shipped. For more information, please contact Streicher’s customer service at, 800-367-3763.