I'll put up sme photos of the "crush". It will only work for thing being done "at the back end", so fine for AI, and for cows that are haltered. It's just a gate hinged on the wall of the byre, with a couple of tie rings - one at the front to tie the cow to and one at the side to put the rope through to lever the gate over, thus holding the cow's hind quarters. The vet said the cow moving forward and back was OK but moving side to side made things very difficult

PRID is progesterone releasing intravaginal device. It releases progesterone for 7 days and this suppresses the oestrus cycle. Once the device is taken out, oestrus occurs in 48 hours, so you can accurately inseminate at the optimum time. Strike rate for single insemination is 55% and that increases with double - second AI 72 hours after removal, which is what we're doing. I think it's used to synchronise batches of heifers and for cows that are hard to see the heat period in. Obviously, other management issues are important too (according to the blurb) but I thik this will be geared towards the dairy industry where AI is the norm and fertility is a problem.
If they don't hold, at least we'll know when to look for bulling. If there's no sign of bulling 21 days after, they'll be PDd 35 days after AI, then we'll know if they are in calf.