manual cam chain tensioner to replace the oe part that runs on oil pressure, 

so chain tends to rattle when first started

 once correctly set  this will not happen

 so will improve the life of your camchain

and no nasty rattle when first starting

we use these in our own race bikes !!

KTM
250 EXCF, XCF, SXF 2007-2019
350 SXF, EXCF, XCF 2011-2019
350 FREERIDE 2013-2015
400, 450, 500, 520 EXCF, XCF 2008-2011
450 SXF, SMR 2007-2012

Husaberg
FE390, FE450, FE570 2010-2012
FE250, FE350 2013-2014

Husqvarna

FC250, FE250, FC350, FE350 2014-2019