Collection of 7 off quartz crystals (1940s) comprising:- (1) Type 6A No.1 - 877 KHz; (2) FT-171-B by Bliley Elect Co., Erie, Penna, Ex BC610 - 1746 KHz; (3) B7G based, type 942 - 4195 KHz; (4) GEC metal based - 2500 KHz probably; (5) TMV 87-A4 - 4637.5 KHz; (6) CR-1A/ AR CZX - 6727.77 KHz; (7) CR-1A/AR CUR - 6497.77 KHz