A gear box produces simple mechanical functions for different movements! Build up several models with one set Age, 8+ Number of models, 10 Number of parts, 220 Erector Set, 10-Model set, #835510E EBM835510ERegular Price: $31.99Sale Price: 31 YEARS OF GREAT LOW HOBBY PRICES If You Have Questions, Please Call Toll Free, 1-800-225-6509 Ask for Doug or Sue