The TBM kit is an upgrade that allows owners of SPRs with the standard DBM magazine assembly (.308 only) to upgrade to the TBM magazine assembly with 5 and 10 round magazines. Kit replaces the trigger guard assembly. Does not require modification or fitting to the rifle. Does not fit SPRs with hinged floorplate. TSRs and PBRs with DBM equipment might require fitting by a gunsmith. Retrofit on SPRs can be accomplished in minutes and requires few tools. Comes with trigger guard/bottom metal, 5 and 10 round TBM magazines, new action screws, and instructions.