2aad6ef1_Coasters_com___Model_Materials__WHAT_IT_IS_USED_FOR
[ITEM] K'nex chain sprockets [WHO MAKES IT] K'nex [WHERE TO GET IT] Ebay will probably be your best bet, K'nex does not sell this part individually or buy a Micro Coaster set from K'nex that has motor, sprocketsand chain [WHAT IT IS USED FOR] 
Chain lift
Model Coasters.com - Model Materials
WHAT IT IS USED FOR