"Sleeves were designed originally to serve as a protective device for records and labels during shipment. In the case of "45" rpm records, however, a device of this nature becomes unnecessary. The raised label area on 45's fully prevents any harmful contact between the grooved surfaces of records during shipment. Paper separators - such as this sheet - are designed to protect record labels during shipment. They have no other useful function and may be discarded at your convenience..."
- Sage record care advice circa 1952, from the folks at RCA Victor
Lifted from Craig Moerer's newsletter
"Sleeves were designed originally to serve as a protective device for records and labels during shipment. In the case of "45" rpm records, however, a device of this nature becomes unnecessary. The raised label area on 45's fully prevents any harmful contact between the grooved surfaces of records during shipment. Paper separators - such as this sheet - are designed to protect record labels during shipment. They have no other useful function and may be discarded at your convenience..."
- Sage record care advice circa 1952, from the folks at RCA Victor