Pistons specs question for 340 build

Hi all - can someone tell me what the -cc value refers to in the specs for the D.S.S Racing forged pistons? I am building a 1971 340 and wanting around 9.8 to 10.2:1 CR (any more than that, even with 98 octane, our fuel is sh** apparently in this country I've been told by foreigners). The two DSS FX1 pistons I'm looking at, one says -5cc and the other -16cc and gives the CR at some specified comb chamber volumes. Are these just referring to different compression heights? The minus should mean reducing the Comb Chamber volume but it seems to be making the CR lower (adding to the volume?).

I only have 360 J heads (1.88) so will need to get them milled for my desired CR (I'm very thankful to see the milling size chart for this in the Sticky section)

I have used KB Hypers several times before but would like to try the forged DSS ones, hoping they are lighter. I am very surprised that I can not see the actual weight of the piston in the specs. Why is that? If that was given then it would be easy to see at a glance the differences in weights between piston brands to help make an informed choice.

PS, I can't afford the SRP or Wiseco or JR pistons - around A$2500+