A plurality of radio devices having a radio communication function establish a radio connection therebetween by exchanging their identifiers, and then exchange their information. of from 4 to 6 cSt, and comprising in admixture 60 wt % to 90 wt % of a first base oil component, based on the total weight of the composition, the first base oil component consisting of a polyalphaolefin base stock or combination of polyalphaolefin base stocks, each having a kinematic viscosity at 100\xb0 C. Preferably at least a portion of the frac plug is a material formulated to decompose in one to twenty-four hours under typical wellbore conditions.