The CRL Low Profile Floor Mounted Door Closers are preferred for many types of installations because they only require a shallow 1-9/16" (40 mm) depth cut out in the floor. This is especially important on floors above the ground floor. The shallow cut out leaves enough remaining floor under the closer to support the weight of heavy doors. The standard spindle collar height supplied with the closer is 1/8" (3 mm). Spindles with other collar heights are available to accommodate different threshold and finished floor heights. The closer has dual independent valves for closing operation, one valve for closing and one valve for latching. Both Hold Open and No Hold Open models are available.