uh - g/mol and "dalton" are equivalent. pubchem lists ibutamoren as "molecular weight: 528.668 g/mol"
https://pubchem.ncbi.nlm.nih.gov/compound/Ibutamoren
actual mk-677 may be even heavier (mesylate) molecular weight: 624.77 see here -
edit: don't know if chem supply houses that sell are allowed - removed link, quote only
Edited Cat#: xxxxxxxx
Name: Ibutamoren mesylate
CAS#: 159752-10-0 (mesylate)
Chemical Formula: C28H40N4O8S2
Exact Mass:
Molecular Weight: 624.77
Elemental Analysis: C, 53.83; H, 6.45; N, 8.97; O, 20.49; S, 10.26
looks too heavy to me?