Bulldog Trailer Jacks are the unquestionable leader in the trailer industry. Since 1919, Bulldog has been manufacturing the industry’s most trusted products for heavy duty applications. Whether it’s for livestock trailers, utility rigs, or cargo haulers, every rugged and proven Bulldog product is certified ASABE S485 compliant – the ”gold standard” in proven performance for telescopic screw-type jacks. Bulldog Trailer Jacks offer you proven quality, performance, and versatility. Our wide range of products has you covered whatever your application. For heavy-duty loads where a combination of speedy operation and a variable cranking ratio is needed, Bulldog 2-Speed Square Jacks are a good solution.