It's really embarrassing getting so much practice saying this, and I wish I could figure out how to avoid what has been happening.
This time its been mountain bike stems for the kits. Being a small business (if there's a size smaller than small then that's what probably applies to me) I can't afford to buy in the quantities that would guarantee me always having a parts inventory. I have a good source for quality stems at an affordable price, and so I've kept a small inventory of stems...enough to enable me to fill orders in a reasonable time.
Until about a month ago all was well. Then the lethal combination of more orders than inventory, and the supplier out of stems occurred. Its taken about 5 weeks to hear from the supplier that my order of stems has finally been shipped. With luck they'll arrive early next week and I'll be able to ship out orders that some of you have been patiently awaiting for far too long.