I like 25g 5/8" for the delts, and 25g 1" for quads. For me? glutes is for if you have somebody else to inject, otherwise this guy doesn't mess with that area. If its injected into a muscle? same difference, all muscles are the same...not like the glutes have any special fibers in there specific for "injecting/absorbing better" just go to the hilt and get in there deep enough. and aspirate for christs sake!