1" PEX with 1/2" Jentro couplings

[GeoMass]

I'm installing 1" ID PEX tubing. I have to connect Jentro brass couplings to each end. The coupling slips inside and is clamped. This reduces the the diameter from 1" ID down to 1/2" ID. Will there be a great pressure drop? The couplings are installed on each end. Does this make this 1" tubing now a 1/2" tubing? The reason for the 1" was to move a larger amount of hot water from 100' away. How will this affect my choice in circulation pumps? Also are there other types of fittings that I can use to keep the 1" spec. of the tubing?

Thanks