Honestly, the biggest thing you need to know up front is the cartridge is sealed in—once that 3ml is done, the whole pen goes in the sharps bin, you can't swap it out, so if you're running a multi-drug protocol this isn't your device, but for a single GLP-1 or insulin course it's pretty much the best fit on the market right now for the money.
You're looking at roughly $4.50 per unit for a sample order of 100 pieces, that drops to about $3.10 in the mid-range around 5,000, and if you're buying 50,000 or so we're talking under $2.60—those prices include teh EO sterilization and a 31G needle already packed, so you're not chasing add-ons.
The dosing is where this thing really earns its keep—from 0.01ml all the way up to 0.6ml in one click increments, and the automatic injection finishes in 6 seconds or less, which your patients will appreciate because nobody wants to stand there holding a button, and the click is loud enough to hear across the room as a confirm.
Its inner cartridge diameter is φ9.7mm, which means it fits standerd 3ml round-bottom cartridges, but—and this is the detail people miss—the pen body itself is only 16mm wide, so it's actually easier to grip than most of the competition, we've had buyers tell us their adherence went up just because of that it didn't feel like a medical tube.
We usually have stock of the 32G needle version, but it takes about 20 days to get the 31G assembled, and the shelf life is a full five years form sterilization date, so you can order a bulk batch and not worry about expiry unless you're sitting on it for half a decade.
The visual window is clear but the markings are in milliliters, not units, so your compounding team needs to double-check conversion for each drug—one buyer almost sent out the wrong instructions because they assumed it was pre-calib insulin units, it's not.