CREATE TABLE table_20297668_1 (standard_yarn_weight_system VARCHAR, wraps_per_inch__wpi_ VARCHAR)

Name the standard yarn weight system for 7 wpi
SELECT standard_yarn_weight_system FROM table_20297668_1 WHERE wraps_per_inch__wpi_ = "7 wpi"
SELECT "standard_yarn_weight_system" FROM "table_20297668_1" WHERE "7 wpi" = "wraps_per_inch__wpi_"