Those are the Gardena brand ones, which are plastic and are the ones that a couple of people have mentioned. I personally haven't had good luck with the plastic ones, but the brass ones are rather more expensive. I looked to see if Harbor Freight had them listed on their website, but I don't see them right now (possibly a seasonal item). Amazon also shows a couple of brass ones. You don't mention where you're located, so I don't know which would suit your needs best. Our local hardware store (Ace Hardware) also carries a brass version. I think these little gadgets are getting more and more popular!
https://www.amazon.com/dp/B0015AUY3W/
https://www.amazon.com/dp/B0008IT0GE/
