AT&T T TEST CORD #AT8987 FITS AT&T 310, 311 SIECOR 391 FRAME TEST SHOE REPAIRED T Test Connector (AT-8987) (Material ID 402 796 841)
Tap Shoe is designed for use with the AT&T's 310/311, and the Siecor 391 Central Office Main Frame Connectors.
Also Commscope 310