▁and ▁d ents ▁would ▁often ▁lead ▁to ▁frequent ▁replacement . ▁ ▁K eller ▁designed ▁the ▁Kel - L ite ▁to ▁be ▁robust . ▁Sales men ▁trained ▁by ▁K eller ▁would ▁demonstrate ▁this ▁for ▁public ▁safety ▁customers ▁by ▁p ounding ▁large ▁n ails ▁into ▁a ▁block ▁of ▁wood , ▁while ▁the ▁light ▁was ▁operating . ▁ ▁Other ▁demonstr ations ▁included ▁throwing ▁the ▁light ▁as ▁hard ▁as ▁possible ▁across ▁a ▁concrete ▁par king ▁lot , ▁or ▁turning ▁the ▁light ▁on ▁and ▁putting ▁it ▁into ▁an ▁aqu arium ▁and ▁driving ▁over ▁it ▁with ▁a ▁tr uck . ▁Nelson ▁also ▁produced ▁a ▁flash light ▁target ed ▁for ▁the ▁tr uck ▁driver ▁known ▁as ▁the ▁Stud - L ite , ▁which ▁was ▁a ▁Kel - L ite ▁flash light ▁with ▁a ▁different ▁name , ▁and ▁an od ized ▁finish . ▁This ▁model ▁was ▁also ▁very ▁popular ▁and ▁sold ▁in ▁tr uck ▁stops , ▁tr uck ▁deal ers hips ▁and ▁parts ▁houses . ▁ ▁The ▁success ▁of ▁the ▁Kel - L ite ▁led ▁to ▁the ▁rise ▁of ▁competition , ▁primarily ▁Mag l ite ▁and ▁Stream light , ▁who ▁improved ▁on ▁K eller ' s ▁basic ▁concept . ▁▁ ▁Stream light ▁opt ed ▁for ▁high - output ▁models ▁using ▁re charge able ▁battery ▁and ▁hal ogen ▁bul b ▁technology . ▁Mag l ite ▁developed ▁an ▁improved ▁switch ▁and ▁a ▁variable - focus ▁system , ▁allowing ▁a ▁single ▁light ▁to ▁be ▁used ▁for ▁a ▁high - int ens ity ▁flash light ▁or ▁wide - angle ▁lan tern . ▁Mag - L