▁It ▁is ▁seen ▁in ▁j um per ▁but ▁not ▁h unter ▁competition ▁Swedish : ▁a ▁" cross - ra il " ▁type ▁of ▁ox er , ▁the ▁highest ▁front ▁and ▁back ▁rails ▁of ▁the ▁ox er ▁form ▁an ▁X ▁when ▁viewed ▁head - on , ▁so ▁that ▁one ▁section ▁of ▁the ▁jump ▁is ▁lower ▁than ▁the ▁other ▁sections . ▁Tri ple ▁Bar : ▁similar ▁to ▁an ▁asc ending ▁ox er , ▁but ▁rather ▁than ▁having ▁two ▁rails ▁there ▁are ▁three , ▁in ▁gradu ating ▁height . ▁This ▁is ▁more ▁difficult ▁than ▁an ▁asc ending ▁ox er , ▁however , ▁because ▁of ▁the ▁added ▁width ▁of ▁the ▁third ▁rail . ▁H ogs back : ▁a ▁type ▁of ▁ox er ▁with ▁three ▁rails ▁in ▁which ▁the ▁tall est ▁pole ▁is ▁in ▁the ▁center . ▁Sometimes ▁this ▁kind ▁of ▁ox er ▁is ▁filled ▁in ▁to ▁look ▁like ▁a ▁bar n ▁or ▁house , ▁which ▁is ▁often ▁used ▁on ▁cross ▁country ▁courses . ▁ ▁Rol lt op ▁These ▁j umps ▁have ▁a ▁rounded ▁half - bar rel ▁appearance ▁on ▁top . ▁They ▁can ▁be ▁quite ▁wide ▁at ▁upper ▁levels , ▁and ▁often ▁govern ▁respect ▁from ▁the ▁horse , ▁but ▁are ▁not ▁usually ▁considered ▁a ▁" sc ary " ▁f ence ▁for ▁horses ▁on ▁course ▁and ▁generally ▁produce ▁a ▁good ▁jump . ▁A ▁modified ▁version ▁of ▁the ▁roll top ▁is ▁sometimes ▁seen ▁in ▁h unter ▁and ▁show j ump ing ▁classes . ▁ ▁Sh ark ' s ▁To oth ▁These ▁f ences ▁have ▁a ▁top ▁log ▁rail ,