Sorry for the long post, but I have an ill-informed and paradoxical answer for you. The mods'll probably slap you down for mentioning the price, which is against the rules in OD - but Mods, ye high and exalted ones, could this thread please remain open once you've snipped the price? Seems like a lot of threads are getting shut down these days in pretty arch tones, and this one concerns a little-known substance that merits discussion.
Searching the net turns up limited and contradictory info on AH-7921: animal studies and forum threads that peg the potency, compared to morphine, at anywhere from 80% to equipotent to '30-40 times stronger but less likely to cause tolerance and addiction' - that last from a wiki piece on 'dermorphin', which it uses interchangeably with the name AH-7921, citing this reference, : ^ Broccardo M, Erspamer V, Falconieri Erspamer G, et al. (1981). "Pharmacological data on dermorphins, a new class of potent opioid peptides from amphibian skin". Br. J. Pharmacol. 73 (3): 625–31. PMC 2071698. PMID 7195758.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2071698.
So I think there may be some confusion here, as other forums disccuss AH-7921 as a synthetic easily cooked up by non-chemists. Either way, given the ambiguity, START SMALL. Like 1mg or less (if you don't have scales that sensitive, RC opiods are Russin roulette with dum-dums). Eyeballing this stuff is a suicide attempt, even if you know and trust the lab - potency is highly uncertain, and your system's swimming in morphine anywy. But the various conflicting threads and journal pieces make it clear that nothing's clear about this stuff - it's stronger than codeine, weaker than fentanyl, may have a higher oral BA than morphine, and may be less inclined to build tolerance and addiction, IF it's synthetic AH-7921, as opposed to te naturally accuring version found in certain ampibians. Bear in mind that freak deaths sometimes occur from OTC meds, RCs are playing chance with your neurotransmitters, and RC opiods are, to my mind, best avoided, as they're probably either weak or lethally strong at 'normal doses'. Given the ambiguity about this one, I suggest making a solution of 1mg/1mls, starting with an an allergy dose of less than half a ml at that concentration, then 1mg if there's no allergic reaction, and if that (as it probably will), has a limited or negligible effect effect, titrate upwards SLOWLY. Keep an anti-histamine at hand as a precaution, but don't use it to frontload/potentiate. You're dealing with a substance of unknown strength - better to underdose than die for a buzz.
But syth'd AH-7921, as opposed to the amphibian variety is claimed to be very easy to make, and 80% - 105% as potent as morphine. This tells you nothing about your tolerance and appropriate dose, because pod grinds' weight doesn't tell us their morphine content, which varies crop to crop, pod to pod and strain to strain. Start with 1mg, give it at least two hours before redosing, and be patient - bear in mind, pods have a very long half-life, so you won't be starting from baseline (or rather, your baseline's swimming in morphine). You may have had good experiences with this source, but that doesn't mean you can rest assured they pulled off a perfect synth. You may not even have received the right compound - they may have produced a near-relative of drasticlly different potency or BA, and you can't be sure of purity. So you don't know what you have (except an opiod habit),and should go into this with maximum caution. Ingest orally, find an effective solvent (water should work - unless you got the frog stuff), and start small, dosing up by increments. Be prepared to get through half the material, before arriving - or not - at a sweet spot - as you increase dose, if necessary, but never take hundreds of mgs at a time. You migh get to a full-blown morphin' power range....
But if you've been on pods at those doses for a while, and it's not te 30 - 40x times stronger stuff, it's not going to be that amazing even if 99% pure. Pods contain a lot of alkaloids in addition to M & ccodeine, and the witdrawal can be as harsh as coming off pharms or street H - and much longer-lasting. So if this is the 80%-as-strong or morphine equipotent stuff, it won't hit all that hard. You have to treat it like potentially fatal, high-power uber-opiate, 'cos it's an RC from an overseas lab, and lots of people have died from those, whatever their tolerance, and this is a basically unknown substance. But pod habits are as serious as H or morph (they are morph, amongst other things), and if you're on decent quality pods, your tolerance may be pretty high. They're also expensive, and seem to leave a permanent base tolerance - it goes down some, but not all that much, with abstinence. I never had a daily pod habit, but owing to their long half-life, still went through withdrawals when I switched to pharms for reasons of access and economy - and I just got through 600mgs of morph over three days, with a day off inbetween, and over a gram of codeine plus potentiators and benzos in the mix. (That's context, not dick-sizing) I realise the above (and I'm still high, so forgive the rambling) seems contradictory, but you have to treat RC opiates as potentially much more potent than pods or pharms - carelessness can equal death, especially when there are such wildly differing claims as to the potency of AH-7921.
So go VERY carefully, leave plenty of time between redosing, start at 1mg and go up by small increments, but be prepared to be underwhelmed. I've taken 100s of of mgs on morph while wearing fent patches, popping xanax and eating dhc (that's why I'm rich and famous - oh, yeah, that's right, my life's a fucking mess), but the only times I've come close to OD'ing have been from strong batches of pods, drinking tea impatiently because of the slow come-up. And....the other bad news. The same amount of morph proper would have cost a whole lot less at UK street prices, without going into specifics.
So treat it like carfentanyl, because RC opiods can be anything at all (you have no idea, for example, how the thebaine in the pods you're taking will interact with AH-7921, they could radically potentiate each other), and
don't eyeball doses - but you may find it was $200 you would have got a lot more out of spent on pods).
Sorry for gibbering - I had a sleepless night, decided to finish off my opiates at 4am, and 150mgs morph + 600 mgs codeine has me long-winded and babbling. Those are obviously pretty high doses, and on the occasions I near-od'd from pods, they were doses of about 500mgs, so my tolerance may be higher and you might have 5 or ten wonderful experiences in tht gram...but I don't think it's been used enough in humans for anyone to give you a definitive answer. (I'm not proud of my tolerance, I'm just very stupid when it comes to moprhia, and moving in with my mom in a few weeks to be in an environment where I'll HAVE to detox) Given the extent of uncertainty, personally, I'd try to find a way to cancel the order and get a refund: or at least abstain from pods for a few days before sampling the AH - the long half-life of pods gives you a grace period before sickness kicks in.)
So play safe, whatever you do, and hope you get something positive from the experience.