I currently have and run a protek 4900 ,reedy 4800 and smc 4000 true spec extreme battery's. on my I charger 406 after 1 cycle (40a discharge 40a charge) the smc has the lowest resistance . The protek and reedy both take about 800 more mah than the smc witch should be expected (4800/4900 vs 4000). The ohms per cell are constantly lower on the smc than the protek and the reedy battery but only like .1-.3 per cell . I only have a few runs on the smc but so far so good , Good punch and its less than half the price of the other two battery's i have . only time will tell we will see how long it lasts but so far i am happy with the performance and very happy with the price . protek and reedy both have great battery's and definitely quality but you get what you pay for