uxcell 0-150V Blue Shell RJ11 Telephone Modem Thunder Arrester Surge Protector Package Included: 1 x Telephone Surge Protector Weight: 92g Dimension: ~8.4(L) x 2.5(W) x 2.5(H)cm Use this RJ11 Arrester to make sure system and equipment when surge come from thunderbolt. All metal cast aluminum enclosure and RJ11 connectors provide for good EMI noise suppression.