Frequently Asked Questions

Does Slick Shield have a Patent?

The Slick Shield technology sought patent protection back in September of 2011. In November 2014 the owners of HMI received notice from the U.S. Patent Office that the application was approved. The patent itself should issue in February 2015 and provide IP protection for this device through the year 2031. See Notice of Allowance.

How can I purchase Slick Shield™ units?

Slick Shield is in the final stages of R & D / Market Research. With enough demand commercial-grade downspout filter units will be mass produced and available for purchase for the 2019-2020 winter season. Businesses interested in purchasing can  contact HMI to provide HMI information on property needs and compatibility.

How much does each unit cost?

Slick Shield kits (device + bellows + connection fixtures) will be offering a discount on the first several thousand units sold at just $49.95 per unit + S/H. As demand increases the price per unit will be raised to $99.95 + S/H. For details on volume discounts contact Darin at 319.350.0466 or email

Will I be able to purchase a small supply (3-4 for my business) or will a bulk purchase be required?

Once Slick Shield is in production, you may purchase small or bulk quantities. Inquire about orders >

Is Slick Shield available for home use?

Yes. The current working prototype to be tooled for mass production will be effective for downspout black ice control in single family residential settings. Just remove your extension for the winter, install Slick Shield for the winter, then switch them back out in the spring.

What are the dimensions of Slick Shield?

The Slick Shield unit is 13” long by 6.5” wide and 8.25” tall. Slick Shield’s flexible bellow can be manipulated for safe and optimal placement on walkways.

How much rock salt does Slick Shield hold?

1 gallon or 9 lbs.

How much rock salt will these units use?

Testing over the past two winters in Iowa has shown that each unit should use around 225 lbs of rock salt over an average winter that includes 25 melt/refreeze events. Using 40 lb bags of rock salt each unit would require approximately 6 bags per winter at cost per bag in the range of $5 – $6 each. At $0.15/lb rock salt (NaCl) is much cheaper than reactively throwing ice melt compounds ($0.50 – $0.60/lb) on black ice patches near your downspouts.

Will the salt brine from the Slick Shield harm our concrete?  

A 2007 Federal Highway Administration and National Department of Transportation sponsored study shows that NaCl brine is actually not harmful to Portland Cement Concrete. It has been studied and compared to other common ice melt compounds including Magnesium Chloride, Calcium Chloride and CMA. To view these government sponsored studies click here. (see pages 162-164)

Are Slick Shield units tripping hazards?

The rubber bellows that connect the downspout to the Slick Shield unit are pliable. The units can be moved easily to reduce the risk of a customer or worker tripping. In two winters of testing at 3 different locations there have been no tripping incidents. Slick Shield units are open, obvious and will be available in fluorescent “caution yellow” for buyers who are concerned about visibility.

Can Slick Shield be removed from downspouts?

Yes. Slick Shield is installed by wrapping the bellow lining around the exterior of the downspout (about 4 inches or more above the downspout opening) and securing with a 12” zip tie. To remove, simply cut the zip tie or slide the bellow off the downspout. Slick Shield is a seasonal product and can be removed at the end of the snow season.

Have a question that’s not listed? Contact HMI and we’d be happy to answer.