used it for a walkon day, seemed fairly average, kept up on psp ramp 15 or 16 bps. uses two 9 volts. it was good but it didn't seem great as the profile was bulky, it was a little annoying to remove the batteries and it has the annoying motor noise whenever you run out. it is heavyish but along the lines of normal loaders. as i say only used it for a day but my overall impressions were pretty good despite a few minor touches- most of which can be found in better hoppers.
i personally thing you should get a second hand halo/reloader for the same or less price as a new eye force.
my two pence