I listed a 208b since its capable of 8S, 106b is only rated to 6S. The 106b you linked is an iCharger made for AMain's house brand ProTek line.

As far as a 4S 5000mah charger is concerend as long as you're happy with either a 1C or 2C charge rate, it'll do a solid job. 1C charge rate dor that 4S is 5amps and 2C would be 10amps.

Charger has 250watts and a 1C charge of a 4S needs only 16.8v x 5a = 84watts, a 2C charge at 10amps would take 168watts. You are limited to 2C since the chargers max charge rate is 10amps.