The 1591AC is a clear polycarbonate lid made to fit the 1591A size of the 1591 series ABS multipurpose enclosures. Swapping it onto a 100 x 50 mm enclosure lets designers and builders see the contents without opening the box.

It is supplied as the lid only. The manufacturer's ordering tables list it as the clear lid accessory for the non-flanged 1591ABK, 1591AGY, 1591ASBK and 1591ASGY, and for the flanged 1591AFLBK, 1591AFLGY, 1591ASFLBK, 1591AF2BK, 1591AF2GY, 1591AF2SBK and 1591AF2SGY. Those enclosures measure 100 x 50 x 25 mm (3.94 x 1.97 x 0.98 in).

The lid itself measures 3.94 x 1.97 x 0.23 in (100 x 50 x 6 mm) and is molded from clear polycarbonate. The enclosure drawings describe it as flame retardant, and the part data gives a UL94 V-0 flame rating and an IP54 rating.

The 1591AC is RoHS and REACH compliant, ships shrink wrapped and has a shipping weight of 0.04 lbs (0.02 kg). Its UPC is 623980545530. Hammond's chemical resistance guidance for polycarbonate and ABS advises against acetone, ketones, strong solvents, thread locking compounds and cutting fluid, so use plastic-safe cleaners.