iBF analogues are starting to appear in Swedish RC shops replacing other fentanyl analogues entirely. The nasal sprays I have seen contain 100 mg in 10 ml water, if the strength comparison with morphine is correct a person used to opiates would have to ingest an entire flask to feel effects. Thus, I am wondering whether this isn't actually 4-Cl-iBF, but a more potent variant. But I have absolutely no clue. The price of the nasal spray is the same as the price for an akrylfentanyl nasal spray which contains enough Fentanyl for 50-100 highs, if the spray contains 4-Cl-iBF the dosage in the spray will only roughly be enough for one high, therefore I cannot imagine that it does contain 4-Cl-iBF. But when the vendor doesn't provide anymore information than the name iBF one can do nothing but speculate. I find it extremely unprofessional and potentially dangerous to sell stuff like this with so little information regarding the actual structure of the chemical.
So far I haven't seen many reports regarding strength and effects.