A foam spring for use in pillows, cushions, mattresses or the like, the foam spring having a tubular resilient body-made of foam with holes extending inwardly from an outside surface to an inside surface, wherein the tubular body-comprises at least one tubular foam layer and at least one reinforcing layer applied to said foam layer over at least a part of the axial length of the spring. The packet transmitting unit transmits to a counter apparatus the first packet that coincides with a packet transmitted immediately before reception of a delay measurement instruction for an IP network between the gateway apparatus and the counter apparatus connected via the IP network. The global word line is decoded via a row decoder. The second polymer, which is advantageously soft and flexible, is applied so that an exposed outer surface of the second polymer corresponds to a portion of the dental instrument to be gripped by a dental practitioner for manual use.